PROBLEM TO BE SOLVED: To provide a muscle force estimation device capable of estimating the maximum muscle force of a subject without giving a large load to become burden on the subject.SOLUTION: A muscle force estimation device giving a load to the muscle of an object region for estimation of the muscle force of a subject so as to estimate the maximum muscle force which the muscle can demonstrate includes: a memory part 40 which previously memorizes an oxygen concentration calculation formula 41 showing a relation between an absorbancy and an oxygen concentration of the object region, and a muscle force calculation regression equation 42 derived from a relation between an evaluation index derived from an oxygen concentration changing with time in blood of the muscle of the object region after giving a small load to the object region, and the maximum muscle force which the muscle of the object region can demonstrate； a measurement part 10 which can measure an absorbancy in the object region； an oxygen concentration calculation part 31 which calculates an oxygen concentration from an absorbancy and the oxygen concentration calculation formula 41； and a maximum muscle force calculation part 32 which calculates the maximum muscle force from an evaluation index and the muscle force calculation regression equation 42.【課題】被験者とって負担となるような大きな負荷を与えることなく、被験者の最大筋力を推定することができる筋力推定装置を提供する。【解決手段】被験者の筋力を推定しようとする対象部位の筋肉に負荷を与えることで該筋肉が発揮可能な最大筋力を推定する筋力推定装置において、対象部位の吸光度と酸素濃度との関係を示す酸素濃度計算式４１と、対象部位に小さな負荷を与えてから該対象部位の筋肉の血中において経時変化する酸素濃度から求まる評価指標と対象部位の筋肉が発揮可能な最大筋力との関係から導出される筋力算出回帰式４２と、をあらかじめ記憶しておく記憶部４０と、対象部位における吸光度を測定可能な測定部１０と、吸光度と酸素濃度計算式４１から酸素濃度を算出する酸素濃度算出部３１と、評価指標と筋力算出回帰式４２から最大筋力を算出する最大筋力算出部３２と、を備えた。【選択図】図２
