To provide a muscle training instrument which has a part to hook feet configured to pull easily by preventing displacement in pulling with the feet hooked and is user-friendly by responding to differences in sizes of feet of users in the muscle training instrument comprising a foot rest member, an expanding and contracting member, and a feet hooking part.

A part of the expanding and contracting member which has flexibility and expanding and contracting features and is formed into a string, belt, chain, or other shape with a certain length is attached to an optional place of the feet rest member having a feet rest part on the upper surface. A feet hooking part which constitutes at least a part of a ring is formed at an end of the expanding and contracting member at a distance from the attached place. The muscle training instrument is characterized by a flexible surface which has a width of at least 5 cm or greater and is formed in a range within 4 cm to the right and left respectively from the end part in the end part of the feet hooking part.