A control device for a human-powered vehicle including a motor that applies a propulsion force to the human-powered vehicle, a crank axle, a driving wheel, and a transmission that automatically changes a transmission ratio of a rotational speed of the driving wheel to a rotational speed of the crank axle in accordance with a travel state of the human-powered vehicle. The control device includes an electronic controller that controls the motor in accordance with a human driving force input to the crank axle. The controller changes an assist state related to at least one of an assist ratio of an assist force by the motor to a predetermined human driving force and the assist force by the motor in accordance with the human driving force and controls the transmission to maintain the transmission ratio upon determining a parameter related to the human driving force satisfies a predetermined condition.