To realize versatility for corresponding to various speed change systems, and to provide a transmission having a simple configuration. A transmission for a motorcycle has a shift pedal elastically inclined up and down from a reference position with a potentio-sensor for detecting the inclination. A control unit determines a shift position value Po obtained from the potentio-sensor, and outputs the shift position value Po to a predetermined speed change coping unit. A comparative determination unit in the control unit determines the inclination of the gear shift pedal through comparing and judging a range B indicative of the reference position, a range N1 set in a predetermined angle range to the lower direction, a range C1 greater in inclination angle than the range N1, a range N2 in a predetermined angle to the upper direction he range B, and a range C2 greater in inclination angle than the range N2.