A stent is formed of a shape-memory alloy and is to be inserted and placed inside a three-dimensional model of a biological organ manufactured for training, under a state in which the stent is mounted on a balloon of a balloon catheter. The stent is expandable under a room temperature environment. When heated to a predetermined temperature higher than room temperature, the stent is contracted until an inner diameter of the stent becomes smaller than an outer diameter of the balloon in a contracted state, and returns to an original shape thereof.