To provide a velocity ratio switching type planetary gear transmission and a velocity ratio switching type planetary gear transmission for a press machine having a velocity ratio switching mechanism incorporated into a planetary gear mechanism capable of suppressing inertia force to be small, formable small as a whole.

This device comprises two rows of sun gears 53 and 54 connected to an input shaft 52, two rows of sun gears 55 and 56 meshed with the two rows of the sum gears 53 and 54, an internal gear 57 slidable in an axial direction selectively meshing with the two rows of planetary gears 55 and 56, and an output shaft 58 connected to the internal gear 57. The internal gear 57 is slid to a specified position by a selecting means 59, and the planetary gear mechanism is made to work in a first row A or a second row B.