A controller of an internal combustion engine includes a sensor, a control unit controlling the engine, and a detector obtaining detection data from the sensor and transmitting the data to the control unit. The detector includes a detection data obtainer obtaining the detection data and storing the detection data in a storage upon having an input of a trigger signal, and a detection data transmitter transmitting the detection data stored in the storage to the control unit, and the control unit includes a trigger output unit outputting the trigger signal at a certain rotation angle timing of the internal combustion engine, and a detection data receiver obtaining the detection data from the detector.