This assisting tool is a multi-functional tool that is used in X-ray measurements of a subject. The multi-functionality is achieved by using the outer form and the inner structure of the tool in combination. More specifically, this assisting tool has two inclined surfaces that constitute the outer form. By inserting this assisting tool under the two legs, the two legs can be kept in a posture in which the knees are bent. The side end structure that constitutes the outer form keeps the two feet in a twisted state. A measurement chamber that constitutes the inner structure is for measuring the forearm.
