A hydraulic brake unit is provided. The hydraulic brake unit includes a manual hydraulic pressure supply unit that pressurizes a hydraulic medium supplied from a reservoir and generates a hydraulic pressure corresponding to a brake operation amount; first and second hydraulic systems in which the manual hydraulic pressure supply unit communicates with first and second wheel cylinders; a separation valve provided between the first hydraulic system and the second hydraulic system; and a brake ECU having a separation valve control unit and a hydraulic medium amount detection unit. The separation valve control unit executes control to close the separation valve when the hydraulic medium amount detection unit detects that the hydraulic medium stored in the reservoir has decreased below a predetermined amount.