To provide a sufficient negative pressure to a brake booster in a simple configuration.

The brake booster includes: a brake booster body 61 provided with a pressure chamber receiving supply of negative pressure of an internal combustion engine; a first negative pressure passage 62 for connecting a part between a throttle valve 11 out of an intake system 1 which is the pressure chamber and an inlet air passage of the internal combustion engine and a surge tank 13 or the surge tank and having a check valve 64 on the way; and a second negative pressure passage 63 for connecting the pressure chamber and a downstream part rather than the surge tank out of the intake system and having a lead valve 66 which is the check valve on the way; and a brake booster 6 for actuating to use the negative pressure supplied to the pressure chamber is provided.