NOVELTY - An arithmetic circuit calculates the dimensionless gravity center position of a user by dividing the rotational torque (T3) with the size of foot and body weight (W) of user. Rotation angle from a rotation angle detector is set to dorsiflexion angle (zeta) of both the feet mounted on pedal boards (1,2). A display device shows the flexibility of a leg by the relationship between dorsiflexion angle and user's dimensionless gravity center position or the relationship between dorsiflexion angle and axial force (P) or the relationship between dorsiflexion angle and rotational torque.    USE - Leg stretch apparatus for displaying or evaluating flexibility of Achilles tendon and calf of leg. Used as flexibility evaluation apparatus and calf stretch apparatus.    ADVANTAGE - Promotes blood flow of leg that is the main generating region of thrombosis while performing bottom dorsiflexion of leg joint of the leg automatically only by setting rotation angle range, time of pedal boards selectively and driving pedal boards to perform stretch exercises of Achilles tendon or calf efficiently. Effect of stretch is directly confirmed through visual observation by quantitatively displaying the relationship of change of rotational torque and rotation angle of pedal boards as flexibility evaluation parameter of user's body during predetermined angle rotation of pedal boards. Performs stretch exercise according to the flexibility level on which evaluation is made easily by performing program control of the pedal boards.    DETAILED DESCRIPTION - Rotational torque (T3) is obtained by the formula T3=PxCn in which P is set as the axial force, and perpendicular distance from axial force and rotary support shaft (D) to a link arm (b) is set to Cn.    DESCRIPTION OF DRAWING(S) - The figure shows a side view of the leg stretch apparatus.    Pedal boards (1,2)    Rotary support shaft (D)    Axial force (P)    Rotational torque (T3)    Body weight (W)    Link arm (b)    Dorsiflexion angle (zeta)