Electronic pen, handwriting input device, and central rod for electronic pen

A handwriting input device, comprising:

• a position detecting device including:
• a magnetic sheet on which a color of a position changes when a magnetic pole nears or contacts the position, and
• a position detection sensor of an electromagnetic induction type disposed under the magnetic sheet in an overlapping manner;
• and
• an electronic pen including:
• a coil,
• a magnetic core around which the coil is wound, the magnetic core having a through-hole in an axial center direction,
• a capacitor that forms a resonant circuit with the coil, and
• a central rod inserted in the through-hole of the magnetic core, the central rod having a magnet part and a yoke part that holds the magnet part at a pen tip part of the central rod;
• wherein,
• the position detection sensor of the position detecting device exchanges a signal, which has a frequency corresponding to a resonant frequency of the resonant circuit, with the resonant circuit of the electronic pen, via electromagnetic induction coupling.

A central rod for an electronic pen, the central rod comprising:

• a pen tip part;
• and
• a shaft,
• wherein,
• the pen tip part has a magnet part and a yoke part that holds the magnet part.