A wheel speed estimation device is to be applied to a four-wheel drive vehicle including a first coupling device for a rear left-wheel axle and a second coupling device for a rear right-wheel axle. These coupling devices respectively change states of engagement of a left engagement state and a right engagement state to the any one of a completely restraint state, a release state, and an incompletely restraint state. The wheel speed estimation device includes a correction parameter calculator that calculates correction parameters affected by a difference in wheel radius between wheels based on all wheel rotation speed signals, and a wheel speed calculator that calculates wheel speeds based on the wheel rotation speed signals and the correction parameters. Further, the correction parameter calculator stops calculation of the correction parameters when at least one of the left engagement state or the right engagement state is the incompletely restraint state.