An injector is provided that includes an injection button and a coil for radiating energy that informs an injection button detection device combined with the injector, of an input of the injection button. The injection button detection device includes a transmitter for radiating an electromagnetic wave associated with a specific voltage to radiate energy that informs an injector combined with the injection button detection device, of an input of an injection button, a receiver for receiving a voltage based on energy radiated from the injector, and a controller for detecting an input of the injection button based on the voltage received from the receiver.
