Abstract: In a hardness tester according to the present invention, an indentor is urged by an indentor spring and moves against the indentor spring when pressed against an object part of a living body. The indentor is inserted in a sleeve which is urged by a sub spring weaker than the indentor spring and moves against the sub spring when pressed against the part of the living body. A converter converts an amount of movement of the indentor into an electrical signal. A trigger generates a trigger signal when the sleeve has moved by a predetermined amount. A control unit carries out a process when receiving the trigger signal, the process including steps of: receiving the digital signal from the converter; displaying the amount of movement of the indentor on a display; storing the amount in a memory unit; calculating a difference in hardness of the part of the living body between a relaxed condition and a strained condition; and displaying the difference on the display.