A variable hardness actuator includes a flexible tubular member； plural particles of magnetic powder filling the tubular member； a coil wound around an outer circumference of the tubular member, surrounding the magnetic powder； a drive unit configured to supply electric current to the coil； and a directing unit used to give a direction to the drive unit to supply the electric current, wherein the coil generates a magnetic field using the electric current supplied from the drive unit in response to the direction from the directing unit, causing the plural particles of magnetic powder to magnetize spontaneously, magnetically couple together, and harden.
