Vehicle brake device

A vehicle brake device comprising:

• first and second master chambers;
• a first master piston driven by any one of an operation force applied to a brake operation member by a driver and a force corresponding to a servo pressure in a servo chamber to generate a first master cylinder pressure in a first master chamber;
• a second master piston driven by a force corresponding to the first master cylinder pressure to generate a second master cylinder pressure in a second master chamber;
• a servo pressure generation portion configured to generate a servo pressure in the servo chamber;
• a failure detection means for detecting a failure of a master system, when a master cylinder pressure correlation value correlated to the first master cylinder pressure is less than a predetermined value, in a case where the first master piston is driven only by the operation force applied to the brake operation member by the driver and either:
• i) an operation amount of the brake operation member is a predetermined amount;
• or ii) the operation force applied to the brake operation member by the driver is a predetermined force;
• and
• driving control means for driving the first master piston by a force corresponding to the servo pressure in the servo chamber generated by the servo pressure generation portion, when the operation amount of the brake operation member by the driver is greater than a predetermined amount or when the operation force applied to the brake operation member by the driver is greater than a predetermined force, in the operation of the brake operation member by the driver in which the failure detection means detects the failure of the master system.