A control device of a transmission is capable of instantaneously correcting a torque shortly after starting a motor, and properly correcting a gear operation shortly after starting (at transient time) even in case of coil temperature change. The device includes a gear change end determination unit, a motor stop determination unit, and a coil resistance estimation unit of estimating a coil resistance of the motor alternately by repeating at regular intervals a state of application of a predetermined voltage to the motor during stop before start of gear change and a state of no application; and when the motor is determined stop by the determination units, an initial value of a command voltage to be applied to the motor after start of gear change is corrected in a predetermined time period in accordance with a coil resistance value having been calculated by the coil resistance estimation unit.