To enable speed change operation with favorable ride comfort in both of semi-automatic control and full automatic control in regard to a speed change controller freely switching between semi-automatic control and full automatic control.

The speed change controller 50 is equipped with a clutch actuator 60, a shift actuator 70, a shift switch 72, a control changing switch 71, and an ECU 90. The ECU 90 has: a driving state detection part 92 detecting a driving state of a motorcycle 1; a semi-automatic control part 93 starting speed change operation in accordance with operation of the shift switch 72; and a full automatic control part 94 starting speed change operation in accordance with detection of the driving state by the driving state detection part 92. In the semi-automatic control part 93, speed change operation is carried out on the basis of first speed change operation specifications in predetermined driving conditions, and in the full-automatic control part 94, speed change operation is carried out on the basis of second speed change operation specifications different from the first speed change operation specifications in the predetermined driving conditions.