A plurality of core bodies are housed within a casing having an opening portion on one end side. A core body selecting mechanism is provided which includes a plurality of operating portions coupled to each of the plurality of core bodies, and makes at least a tip of one core body among the plurality of core bodies selectively project from the opening portion of the casing. A pen pressure detecting portion common to the plurality of core bodies is provided within the casing. When the operating portion is operated to make at least the tip of the one core body project from the opening portion, part of the operated operating portion engages with the pen pressure detecting portion common to the plurality of core bodies, and the pen pressure detecting portion detects a pen pressure applied to the tip projected from the opening portion.