A controller of a laser ignition engine configured to perform ignition by using a laser ignition device configured to emit a laser beam condensed by a lens includes: a combustion state related value acquiring portion configured to acquire a combustion state related value related to a combustion state of the engine; and a contamination determining portion configured to compare the combustion state related value acquired by the combustion state related value acquiring portion with a combustion state determining value to determine whether or not the laser ignition device is contaminated, the combustion state determining value being defined based on the combustion state of the engine when the laser ignition device is not contaminated.