An image pickup apparatus configured to execute wireless communication with a flash apparatus by radio waves via a communication unit includes a signal output unit configured to output a flash start signal to the flash apparatus, a flash detection unit configured to detect a flash emitted by the flash apparatus according to the flash start signal, an acquisition unit configured to acquire a time difference between a predetermined reference timing and a timing at which the flash is regarded to have been emitted by the flash apparatus according to a result of detection by the flash detection unit, and a control unit configured to control at least one of a timing of output of the flash start signal to the flash apparatus by the signal output unit and a timing of start of an operation executed corresponding to the flash by the flash apparatus according to the time difference acquired by the acquisition unit.