CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

[Problem to be Solved] The combustion state is prevented from becoming unstable when an operating point fluctuates in a pre-chamber internal combustion engine.[Solution] In an internal combustion engine including: a combustion chamber; a pre-chamber communicating with an upper center part of the combustion chamber via an injection hole; a fuel injection valve that injects fuel into an intake passage; first ignition means that faces an inside of the pre-chamber; and second ignition means that faces the combustion chamber, the control device is configured to perform: (i) a first combustion mode that performs ignition in the pre-chamber (50) by the first ignition means (5) in a steady state, (ii) transition to a second combustion mode that performs ignition in the combustion chamber (20) by the second ignition means (7) when a change in an operating point is determined in the steady state; (iii) transition to a third combustion mode that performs ignition by both of the first ignition means (5) and the second ignition means (7) when transition of the operating point is completed and it is determined that combustion of the second combustion mode is stable, and (iv) transition to the first combustion mode when it is determined that combustion of the third combustion mode is stable.