Golf putting practice device and auxiliary fastening unit for putter head

A golf putting practice device, comprising:

• a support;
• a rotary body installed in the support rotatably around a rotation axis installed at a central part, including parallel rails, and having a greater curvature than a trajectory formed by a putter head when putting;
• an elastic member installed on one or two sides of the rotary body with respect to the rotation axis to apply an elastic force to allow the rotary body to make a rotational motion such that two front ends of the rotary body move up and down in an alternating manner;
• and
• a mounting part which is movable along the parallel rails,
• wherein the mounting part is installed such that the putter head is detachably attached to the mounting part, and
• the mounting part moves along the parallel rails with the movement of the putter head when putting, and in response to the trajectory formed by the putter head, the rotary body makes the rotational motion around the rotation axis by overcoming the elastic force of the elastic member such that the two front ends of the rotary body move up and down in an alternating manner, and accordingly the mounting part and the parallel rails are kept in close contact, and the mounting part is kept tightly fastened to the putter head.