To provide a transmission device for motorcycle provided with a compact shift mechanism.

This transmission device comprises: a shift mechanism 66 comprising a change pedal shaft 76; a change pedal arm 77 for foot operation the base end part of which is mounted on one end of the change pedal shaft 76; a means 88 for regulating the rocking range of the change arm 77 rocked about the change pedal shaft 76; a shift cam 78 for sliding a shifter fork 77 to move a mission gear 57 on a shaft 52; a positioning cam 84 provided to be integrally rotatable with the shift cam 78; and the positioning means 90 of the shift cam 78 rockably arranged and engageable with the positioning cam 84. The positioning means 90 of the shift cam 78 is provided concentrically with the rocking range regulating means 88 of the change arm 77, and an the rocking range regulating means 88 of the change arm is set as the rocking fulcrum of the positioning means 90 of the shift cam 78.