To solve the problem that it is hard to do up a button and to undo the button depending on a fabric of clothes or the like since the buttons normally used are made of a rigid body with fixed shapes and dimensions, and that it is especially hard for infants, elderly people, and handicapped persons to handle the buttons.

A button is fixed on one side of the clothes or the like, and a button hole is provided at a part where the clothes or the like is superposed on the other side of the clothes in a manner to face the button. The button is constituted to button up or to unbutton by penetrating the button through the button hole. Since the size of the button is varied by forming the button with a base member attached to the clothes or the like and a surface layer member attached to move to the base member mutually, the button enables infants, elderly people, and handicapped persons to do up the button or undo the button easily without exerting great force.