A brake control device capable of preventing a braking force from being excessive when information cannot be transmitted between a first control unit configured to control operation of a boost mechanism and a second control unit configured to control operation of a hydraulic control mechanism. When a second ECU (32) cannot transmit information to a first ECU (26) due to a disconnection of a signal line (27), the second ECU carries out backup control of detecting a braking operation amount of a driver based on signal input from hydraulic pressure sensors (29), and operating a hydraulic pressure supply device (30) based on the detected braking operation amount, to thereby pressurize insides of wheel cylinders. In this case, the second ECU decreases a pressurization amount of a pressure inside the wheel cylinders when a pressure of a master cylinder (8) exceeds a predetermined value (PM0) during the backup control.