A hydraulic unit for a vehicle brake apparatus having a master cylinder and a wheel cylinder includes a housing formed with a pipe line connecting between the master cylinder and the wheel cylinder, a pump disposed in the housing for sucking and discharging a brake fluid to boost pressure of the brake fluid, and a reservoir piston disposed in a hole formed in the housing so as to be movable slidably back and forth, the reservoir piston partitioning a reservoir chamber within the hole for temporarily storing the brake fluid discharged from the wheel cylinder. The hydraulic unit further includes a cover disposed in the hole to close one end on an atmospheric side of the hole, the cover being formed with a fluid reservoir chamber for storing the brake fluid leaking from the pump.