A keypad assembly includes an operation member deformed according to user's manipulation to operate key switches, a binding member disposed on a top surface of the operation member, binding pieces extending and bent from the binding member to enclose sides of the operation member on an edge of the binding member, and a manipulation member disposed on a top surface of the binding member, the manipulation member including at least one key tops, in which the binding members are bound onto inner side walls of a housing of the portable terminal.