An electronic pen comprising: an electronic pen body including: a first position designator configured to transmit a signal to a position detection sensor; a controller; a first connector; an internal power supply configured to be charged from an external power supply via the first connector; and a wireless transmitter; and an expansion device including: a second position designator configured to designate a position in an area of a display screen different from an input area of the position detection sensor; a switch configured to receive an operation performed by a user; and a second connector, wherein the electronic pen body and the expansion device are attachable to and detachable from each other via the first connector and the second connector, wherein, when the electronic pen body and the expansion device are connected to each other, the internal power supply of the electronic pen body is enabled to feed power to the expansion device, wherein the controller of the electronic pen body controls a supply of power from the internal power supply of the electronic pen body to the expansion device, wherein, when connected to each other, the electronic pen body and the expansion device are configured to exchange data therebetween, wherein, when the switch is operated, the controller performs control to receive an instruction from the second position designator and to transmit the instruction received from the second position designator via the wireless transmitter to move a position designator displayed on the display screen when the first position designator of the electronic pen body is detached from the position detection sensor. an electronic pen body including: a first position designator configured to transmit a signal to a position detection sensor; a controller; a first connector; an internal power supply configured to be charged from an external power supply via the first connector; and a wireless transmitter; and a first position designator configured to transmit a signal to a position detection sensor; a controller; a first connector; an internal power supply configured to be charged from an external power supply via the first connector; and a wireless transmitter; and an expansion device including: a second position designator configured to designate a position in an area of a display screen different from an input area of the position detection sensor; a switch configured to receive an operation performed by a user; and a second connector, a second position designator configured to designate a position in an area of a display screen different from an input area of the position detection sensor; a switch configured to receive an operation performed by a user; and a second connector, wherein the electronic pen body and the expansion device are attachable to and detachable from each other via the first connector and the second connector, wherein, when the electronic pen body and the expansion device are connected to each other, the internal power supply of the electronic pen body is enabled to feed power to the expansion device, wherein the controller of the electronic pen body controls a supply of power from the internal power supply of the electronic pen body to the expansion device, wherein, when connected to each other, the electronic pen body and the expansion device are configured to exchange data therebetween, wherein, when the switch is operated, the controller performs control to receive an instruction from the second position designator and to transmit the instruction received from the second position designator via the wireless transmitter to move a position designator displayed on the display screen when the first position designator of the electronic pen body is detached from the position detection sensor.