PROBLEM TO BE SOLVED: To provide a protective device in which a protected part is prevented from becoming critical posture without obstructing the moderate bend of the protected part.SOLUTION: A protective device being one embodiment of the present invention comprises: decision means (e.g., a decision unit 430) for deciding a mode of the physical action for changing rigidity (e.g., degassing action to the air bag, low frequency current flowing action in abdomen abdominal muscle) of a variable rigid body (e.g., an air bag, an abdomen muscular group) being inside (e.g., a ventral side) of a bend part (e.g., a waist) according to a posture of the protected part including the bend part； and instruction means (e.g., an instruction unit 450) for instructing execution means (e.g., a statement part 460) so as to bring the physical action according to the mode to at least a portion of the variable rigid body whenever the mode is decided by the decision means.SELECTED DRAWING: Figure 5【課題】保護対象部位の適度な屈曲を妨害することなく当該部位が危険な姿勢になることを阻止する。【解決手段】本発明の一態様である保護装置は、屈曲部位（例えば、腰部）の内側（例えば、腹側）にある可変剛性体（例えば、エアバッグ，腹部筋肉群）の剛性を変化させる物理的作用（例えば、エアバッグに対する脱気作用，腹部腹筋群に低周波電流を流す作用）の態様を、該屈曲部位を含む保護対象部位の姿勢に応じて決定する決定手段（例えば、決定部４３０）と、前記決定手段により態様が決定される度に、該態様に応じた前記物理的作用を前記可変剛性体の少なくとも一部に対して及ぼすよう実行手段（例えば、実行部４６０）に指示する指示手段（例えば、指示部４５０）と、を具備する。【選択図】図５
