A variable hardness actuator includes a first flexible member to which a first electrode is fixed, a second flexible member disposed to be opposed to the first flexible member, a second electrode being fixed to the second flexible member, an insulating member configured to insulate the electrodes, a driving section configured to apply voltages to the electrodes, and an instructing section configured to instruct the driving section to apply a voltage. When the driving section applies the voltage according to the instruction from the instructing section, electrostatic attraction is generated between the electrodes and a frictional force is generated between the flexible members. The flexible members integrally harden against a bending force from an outside.