In a startup operation of an internal combustion engine, the internal combustion engine is started by supplying fuel to only a first cylinder group formed of a portion of cylinders, from among a plurality of cylinders that make up the internal combustion engine, when a startup condition of the internal combustion engine has been satisfied, and then fuel starts to be supplied to a second cylinder group formed of the remaining cylinders after the internal combustion engine has started. Meanwhile, in a stopping operation of the internal combustion engine, the internal combustion engine is stopped when a shutoff condition of the internal combustion engine is satisfied, by first stopping the supply of fuel to the second cylinder group and then stopping the supply of fuel to the first cylinder group after the supply of fuel to the second cylinder group has been stopped.