Anti-skid control is performed by switching between a reduction mode for reducing braking torque and an increase mode for increasing braking torque based on a comparison between four wheel speeds and vehicle body speed. A controller calculates wheel accelerations based on wheel speeds and includes a control mode condition where the reduction mode is selected at each wheel and a wheel acceleration condition where each wheel acceleration is within a predetermined value range. If a state in which the control mode condition and the wheel acceleration condition are simultaneously satisfied is maintained over a predetermined time period, the controller determines that a residual state is satisfied. When the residual state is not satisfied, the controller calculates vehicle body speed based on the maximum value of the wheel speeds, whereas when the residual state is satisfied, the controller calculates vehicle body speed based on the minimum value of the wheel speeds.