A brake apparatus for a vehicle comprising: an operation member on which a braking operation is performed by an occupant; a master cylinder (111; 611; 711) in which a front pressure chamber (R 1) is defined by movably supporting a drive piston (113; 613; 114; 614; 713, 714) in a cylinder and which can output a hydraulic pressure in the front pressure chamber (R 1) by moving the drive piston (113; 613; 114; 614; 713, 714) by the operation member; a control pressure setting unit for setting a target control pressure according to an operation force input from the operation member to the drive piston (113; 613; 114; 614; 713, 714); a hydraulic pressure supplying source (38; 122; 42; 127); a front wheel cylinder (21 FR; 21 FL) coupled to the front pressure chamber (R 1) and generating a braking force to a front wheel; and a pressure control valve (44; 631) capable of adjusting a hydraulic pressure from the hydraulic pressure supplying source (38; 122; 42; 127) by moving a drive valve (56; 514) by an electromagnetic force on the basis of the target control pressure, outputting the adjusted hydraulic pressure to a rear wheel cylinder (21 RR; 21 RL), adjusting a hydraulic pressure from the hydraulic pressure supplying source (38; 122; 42; 127) by moving the drive valve (56; 514) by an external piston (58; 632) which is moved by the hydraulic pressure from the front pressure chamber (R 1), characterized in that said master cylinder (111; 611; 711) further comprises a rear pressure chamber (R 2), also defined by movably supporting said drive piston (113; 613; 114; 614; 713, 714), in that the adjusted hydraulic pressure is further outputted to the rear pressure chamber (R 2), and in that the drive piston (113; 613; 114; 614; 713, 714) has an input piston (113; 613) and a pressure piston (114; 614) disposed in series in the cylinder, the rear wheel cylinder (21 RR, 21 RL) is coupled to the rear pressure chamber (R 2) and generating a braking force to a rear wheel (RR, RL), an operation force on the operation member can be entered to the input piston (113; 613), the front pressure chamber (R 1) is defined in front of the pressure piston (114; 614), the rear pressure chamber (R 2) is defined between the input piston (113; 613) and the pressure piston (114; 614), a reaction force chamber (R 4) is defined for the input piston (113; 613), and the hydraulic pressure supplying source (38; 122; 42; 127) is coupled to the reaction force chamber (R 4) via a reaction force control valve (132; 636). an operation member on which a braking operation is performed by an occupant; a master cylinder (111; 611; 711) in which a front pressure chamber (R 1) is defined by movably supporting a drive piston (113; 613; 114; 614; 713, 714) in a cylinder and which can output a hydraulic pressure in the front pressure chamber (R 1) by moving the drive piston (113; 613; 114; 614; 713, 714) by the operation member; a control pressure setting unit for setting a target control pressure according to an operation force input from the operation member to the drive piston (113; 613; 114; 614; 713, 714); a hydraulic pressure supplying source (38; 122; 42; 127); a front wheel cylinder (21 FR; 21 FL) coupled to the front pressure chamber (R 1) and generating a braking force to a front wheel; and a pressure control valve (44; 631) capable of adjusting a hydraulic pressure from the hydraulic pressure supplying source (38; 122; 42; 127) by moving a drive valve (56; 514) by an electromagnetic force on the basis of the target control pressure, outputting the adjusted hydraulic pressure to a rear wheel cylinder (21 RR; 21 RL), adjusting a hydraulic pressure from the hydraulic pressure supplying source (38; 122; 42; 127) by moving the drive valve (56; 514) by an external piston (58; 632) which is moved by the hydraulic pressure from the front pressure chamber (R 1),