The movie starts with Nobita seeing a mysterious pink gas at his house. He enters it and arrives at a planet where all animals that can talk. When he wakes up, he tells his dream to his friends. But they do not believe him. When back home, he sees a flower which he had taken from that planet.

That night, Nobita goes to the bathroom and discovers the mysterious pink gas for the second time. When he enters it, Nobita arrives at a forest. Doraemon then takes Nobita when strong wind occurs, Nobita says that his objective is to meet with the animals. They use the bamboo copter to fly, they later discover a little dog at the river on a raft floating on the river. Nobita helps it to the city that he saw. Finally, the little dog meets with its father while that finally revealed that the name of that dog was Chippo. Nobita is invited for a tea party at Chippo's family house, Chippo asks Nobita's where he is from. He told he comes from Tokyo, but Chippo doesn't know where or what is Tokyo. However, Nobita and Doraemon needs to go home using the bamboo copter, they fly back through to the pink gas.

During their time there, they found that the moon of that planet was very big; larger than one seen from Earth. They finally realized that this was a different planet. And it only can be accessed from the pink gas. In the meantime, it is revealed that development would occur on the mountain and during Doraemon's attempt to protect the area, they find out another entrance to the planet. The next time they go, they bring Shizuka along which makes Gian and Suneo suspicious of them and follow them as well. Once they do get through, the first three land in the city during its new year celebration where they disguise themselves as the planet's inhabitants, it is revealed that someone had brought their ancestors there after something had gone wrong on the planet's moon, Gian and Suneo get stuck in a forest then attempt to go back through the gas to find a planet in ruins and run back once they find someone trying to go through with Gian fearing coming back to said forest again.

The first three realize that Gian and Suneo had arrived once some of the inhabitants reported that a gorilla and fox who are wouldn't talk were at a police station, when they do get there they give Gian and Suneo their respective disguises and attempt to return home. However, Gian staunchly refuses to go with them until the Gorilla who found him earlier shows up and he rushes past all of them. They then use the machine they spotted over there to return Earth.

Nobita on the next day sees that the flower from the planet had wilted and thinks that the planet is currently in trouble, however his mother uses up his room to study about environmentalism and is unable to confirm anything. Gian and later Nobita's mother say that they had been hearing strange voices recently and Doraemon figures that the planet is currently in trouble and uses the Space Exploration Boat to return to the Animal Planet.

Upon arrival, they find the entire planet deserted and in ruins and rescue Chippo who had been buried under rubble trying to save his cousin, Romi. The invaders then announce they had captured Romi as a hostage and Nobita rides a spaceship to go to the planet to rescue her. When he arrives on the planet, he finds the planet in even worse state and steals a suit from one of the guards who tells their leader of a spy. While on there, it is revealed that they are the Nimuge and are bitter that they live in ruins while the animals on the planet's moon are living much better than they are. When they check for a spy, it is revealed there is another spy who does get caught but both of them along with Romi manage to escape the planet before their recapture.

Meanwhile, on the animal planet, Doraemon devises a defense plan and him along with Nobita's friends and Chippo, greet Nobita and Romi once they arrive safely back. Once the invaders arrive back the next day, the use Air Cannons which were able to disable most of the ships and forced them to all land. Doraemon improvises when their cannons are unable to penetrate their suits. Forced to retreat, the Nimuge commander orders attempts to burn the forest but is foiled all the while another fleet of ships approaches from behind. To the relief of the animals and Doraemon they are the police who arrest the Nimuge which are a secret organization. The police force expresses their regret for their actions and their desire to make amends with the animal planet.

The movie ends with them heading back home after the Space Exploration Boat is fished out of the river in the animal planet, once they do come back it is revealed that development on the mountain was halted as well.

• The film was released in Japan on 10 March 1990.
• The Tagalog dubbed of the film was released on GMA television on 1 July 2012.

Chippo

He is a humanoid dog from the animal planet. He is the Key Character of the Film. He was a good friend of Nobita and Doraemon. They first met when he was caught on a storm and Nobita Saved Him. He likes to do Adventure.

Romi

She is the Cousin of Chippo. When She was captured by the Nimuges, Nobita went to the planet and Saved Her from Them. Through the movie, she was not introduced to anyone except Nobita. She and Nobita are Good Friends.

Chippo's Father

He is the Father of Chippo. He is the Policeman of the Neighborhood.

Nimuges

They were Members of Cockroach Group who wanted to Invade Animal Planet.

• Doraemon The Movie 25th page (in Japanese)
• Doraemon: Nobita and the Animal Planet at IMDb