The variable hardness actuator (10) is attached to the flexible member and has a function of providing the flexible member with different hardness. The hardness variable actuator (10) includes a shape memory member (20) whose phase can be changed between the first phase and the second phase, and the shape memory member (20) between the first phase and the second phase. The induction member (30) which causes the phase transition of the above and the cooling mechanism (70) for cooling the shape memory member (20) are provided. When the shape memory member (20) is in the first phase, the shape memory member (20) takes a soft state that can be easily deformed according to the external force, provides the flexible member with low hardness, and when in the second phase, the external force The hard state which shows the tendency to take a memory shape against is taken, and high hardness is provided to a flexible member. The cooling mechanism (70) includes a heat transfer medium (72) that promotes heat dissipation of at least a portion of the shape memory member (20).硬度可変アクチュエータ（１０）は、可撓性部材に装着されて可撓性部材に異なる硬度を提供する機能を有する。硬度可変アクチュエータ（１０）は、第一の相と第二の相の間で相が移り変わり得る形状記憶部材（２０）と、形状記憶部材（２０）に第一の相と第二の相の間の相の移り変わりを引き起こさせる誘起部材（３０）と、形状記憶部材（２０）を冷却する冷却機構（７０）を備えている。形状記憶部材（２０）は、第一の相にあるときは、外力に従って容易に変形し得る軟質状態を取り、可撓性部材に低い硬度を提供し、第二の相にあるときは、外力に抗して記憶形状を取る傾向を示す硬質状態を取り、可撓性部材に高い硬度を提供する。冷却機構（７０）は、形状記憶部材（２０）の少なくとも一部分の放熱を促進する熱伝達媒体（７２）を含んでいる。
