An input pen comprising: a wood shaft, a mounting hole that is formed at an axial center of the wood shaft, and an input body that is rod-shaped and is mounted in the mounting hole, wherein an inner side surface of the mounting hole and an outer side surface of the input body are removably fixed, wherein the input body comprises an outer tube, a digitizer unit built-into the interior of the outer tube, a rod-shaped ferrite core that is positioned at an axial center, an electromagnetic induction coil that is disposed at an outer periphery of the ferrite core, wherein the digitizer unit has a structure in which the rod-shaped ferrite core is mounted via a distal end coupling to the distal end of an accommodating tube, a contacting distal tip that is fixed to a distal end of the ferrite core, and a writing pressure sensing portion in accordance with a variable capacitance capacitor that senses pressing force applied to the contacting distal tip, wherein the writing pressure sensing portion is mounted to the rear end of the accommodating tube, wherein the input body is configured as a refill and further comprises a second capacitor, wherein the ferrite core, the electromagnetic induction coil, the writing pressure sensing section and the second capacitor are electronic parts that are built-in within the input body, and form a parallel resonance circuit, wherein: the input body is accommodated in the mounting hole, an insertion restricting portion, which demarcates an insertion limit of the input body in the mounting hole, is provided at a midway portion of the wood shaft, and a rear end of the input body is formed as a press-contact portion that press-contacts the insertion restricting portion. a wood shaft, a mounting hole that is formed at an axial center of the wood shaft, and an input body that is rod-shaped and is mounted in the mounting hole, wherein an inner side surface of the mounting hole and an outer side surface of the input body are removably fixed, wherein the input body comprises an outer tube, a digitizer unit built-into the interior of the outer tube, a rod-shaped ferrite core that is positioned at an axial center, an electromagnetic induction coil that is disposed at an outer periphery of the ferrite core, wherein the digitizer unit has a structure in which the rod-shaped ferrite core is mounted via a distal end coupling to the distal end of an accommodating tube, a contacting distal tip that is fixed to a distal end of the ferrite core, and a writing pressure sensing portion in accordance with a variable capacitance capacitor that senses pressing force applied to the contacting distal tip, wherein the writing pressure sensing portion is mounted to the rear end of the accommodating tube, wherein the input body is configured as a refill and further comprises a second capacitor, wherein the ferrite core, the electromagnetic induction coil, the writing pressure sensing section and the second capacitor are electronic parts that are built-in within the input body, and form a parallel resonance circuit, wherein: the input body is accommodated in the mounting hole, an insertion restricting portion, which demarcates an insertion limit of the input body in the mounting hole, is provided at a midway portion of the wood shaft, and a rear end of the input body is formed as a press-contact portion that press-contacts the insertion restricting portion. the input body is accommodated in the mounting hole, an insertion restricting portion, which demarcates an insertion limit of the input body in the mounting hole, is provided at a midway portion of the wood shaft, and a rear end of the input body is formed as a press-contact portion that press-contacts the insertion restricting portion.