A sensor included in each brake system section detects the operation state of an electric parking brake in another brake system section. Based on the detected operation state, the sensor assumes the drive command that is to be output from a controller of the other brake system section to a controller of its own brake system section. The controller of one brake system receives an input of a drive command that is output from the controller of the other brake system. The controller of one brake system compares the assumed drive command (internal value) with the input drive command (input value). When the internal value and the input value do not match, the controller determines that an abnormality has occurred in the other brake system section.