Normally, at the time of cold-start of an internal combustion engine or the like, the flow of exhaust in an exhaust passage of the internal combustion engine is suppressed or two-stage combustion is carried out so as to promote exhaust purification in an exhaust system. However, when a correlation value of a braking force required to be generated by a vacuum type brake booster is greater than a correlation value of a braking force that can be actually generated by the vacuum type brake booster, a restricting device restricts the suppression of the exhaust flow or a two-stage combustion prohibiting device prohibits the two-combustion.