An automatic coin collection device for a payphone provided with no coin collection signal is disclosed, which has a solenoid to be activated to collect coins so as to start to count time and begin telephone communication. A call tone detector is connected to a telephone line for detecting a call tone on the line. A voice detecting circuit is connected to the telephone line for detecting a voice signal on the line. A micro-controller is provided for analyzing the detecting results of the call tone detector and the voice detecting circuit after dialing to activate the solenoid when a ring back tone disappears and a voice signal appears, or when no ring back tone is detected but a voice signal appears. With this, the user can use a payphone to make a phone call without the need of pressing a pushbutton to collect coins.