An image capture system includes an image capture apparatus and an accessory connected to the image capture apparatus. The accessory includes a signal terminal used to communicate with the image capture apparatus based on a voltage value or current value, an activation signal generation unit which generates an activation signal required to switch the image capture apparatus from an idle state to a non-idle state, and a control unit which controls to output the activation signal to the image capture apparatus via the signal terminal. The image capture apparatus includes a state change unit which changes a state of the image capture apparatus between the idle state and non-idle state. The state change unit changes the state of the image capture apparatus to the non-idle state upon acceptance of the activation signal via the signal terminal in the idle state.