There are provided a resin double helical gear capable of reducing operation noises and vibrations of an ink jet printer, and a gear train for an ink jet printer using the same. The gear train 2 for an ink jet printer 1 includes an output gear 5 of a motor 3, a first idle gear 6 meshing with the output gear 5, a second idle gear 7 rotatable with the first idle gear 6, and a driven gear 8 which is mounted on a roller shaft 13 so as to be rotatable therewith and which meshes with the second idle gear 7, wherein a resin double helical gear 101 is used as each of the output gear and the first idle gear, and a spur gear is used as each of the second idle gear and the driven gear. The resin double helical gear may have a meshing relief portion 113 by cutting a chevron-shaped top portion 104 in a central portion 103 in face width directions, which is arranged in a butt portion 113 between a first die 108 and a second die 110, from a tooth crest to a portion near a bottom land so as to decrease a tooth thickness.