A brake control device for a brake system. The control device can perform both an interlocking brake control and an antilock brake control. The brake system includes a front-wheel hydraulic circuit, a front-wheel-side braking part; a rear-wheel hydraulic circuit, a rear-wheel-side braking part; and an electrically-operated pump which pressurizes the brake fluid. The brake control device includes a usual voltage mode where the interlocking brake control or the anti-lock brake control is performed when the supply voltage is a first voltage or more, and a low voltage mode where at least one of the interlocking brake control and the anti-lock brake control is performed in a limited manner when the supplied voltage is a second, lower voltage. An operation mode is changed from the usual voltage mode to the low voltage mode when it is determined that the supply voltage becomes lower than the first voltage.