PURPOSE: To directly measure an elastic modulus of a completed product and to read a measured result in a static state by providing a support member connectible in an oscillatory return passage at a scale member approached to a moving track of an oscillatorily hung weight.

CONSTITUTION: A distance between holders 7 and 8 is previously regulated to match a length of a platen P to be measured, and a shaft Pa of the platen is inserted into and held in engaging grooves 7a, 8a of the holders 7, 8. In this case, a hanging member 6 and a scale member 11 are so moved that a weight 10 is brought into contact with a position to be measured of the platen P, and so fixed as not to be moved. When the weight 10 is moved to a predetermined position by a scale of a scale indicator 11a of the member 11 in this state, to a chain line state and the weight 10 is then released, an end face of the weight 10 is collided with the platen P. In this case, since an impact force of the shaft Pa of the platen P is received by left vertical surfaces of the grooves 7a, 8a of the holders 7, 8, the platen P is not moved, and can be accurately measured.