1/42 is the only live recorded album for the Japanese band Mr.Children, released as a limited edition with 500,000 units in September 1999.^[1]

1/42
Live album by Mr. Children
Released	September 8, 1999
Recorded	June 26, 1999, at the Makomanai Ice Arena, Sapporo, Hokkaidō, Japan (except the bonus track "Dakishimetai" recorded at Ginowan Seaside Park, Ginowan, Okinawa, Japan)
Genre	Pop rock, power pop, progressive rock, alternative rock
Length	48:42 (Disc 1) 62:24 (Disc 2)
Label	Toy's Factory
Producer	Takeshi Kobayahi
Mr. Children chronology
Discovery (1999) 1/42 (1999) Q (2000)

Its title was derived from the number of the places where the band played on that year's their concert tour entitled Discovery. All tracks were adopted from the live performance at the Makomanai Ice Arena, recorded on July 26, 1999, except for the additional track "Dakishimetai" that was recorded in the gig at the Okinawa Ginowan Seaside Park.

The double album debuted at the position of #1 on the Japanese Oricon albums chart and sold out 7 weeks later from its release. Finally the album was certified RIAJ double-platinum status, selling estimated more than 500,000 copies.