To secure sufficient negative pressure necessary for operations of a brake booster even if there is a variation in atmospheric pressure, in an internal combustion engine being composed of installing this brake booster.

A fuel injection valve 11 is set up in an inner wall peripheral part of a cylinder heat 4 in and around both first and second inlet valve 6a and 6b of an engine 1, and fuel out of this fuel injection valve 11 is directly sprayed into a cylinder 1a. In addition, a brake booster 71 to secure the braking force of a vehicle is installed in an air intake duct 20 at the more downstream side than an electronic controlled type throttle valve 23. An electronic control unit(ECU) 30 calculates a difference between the atmospheric pressure and brake booster inner pressure being detected by a pressure sensor 63 as brake booster inner relative pressure, and in the case where it is smaller than the reference value, confinement control of the throttle valve 23 is executed.