Control apparatus for engine, power unit of saddle-riding type vehicle, saddle-riding type vehicle and method for controlling an engine

Knocking can be favorably handled in a saddle-riding type vehicle even if exogenous noise is mixed in the output of a knock sensor due to collision of a small stone or the like. The saddle-riding type vehicle includes: a first acquisition section that acquires a signal output from the knock sensor during a first period during which there is a possibility of occurrence of knocking; a second acquisition section that acquires a signal output from the knock sensor during a second period which is at least part of a period of the engine excluding the first period and excluding a period during which noise caused by mechanical vibration of the engine is generated; a first control section that determines occurrence of knocking based on the signal acquired by the first acquisition section and that controls the engine to suppress the knocking when knocking occurs; and a second control section that determines generating of exogenous noise caused by an external situation of the saddle-riding type vehicle based on the signal acquired by the second acquisition section and that changes the control of the engine by the first control section based on the determination result.