An electric plug for use in a mobile telephone to connect an electronic component to a circuit board is disclosed to include a plug body and two terminals fastened to a respective terminal slot in the plug body and connected to a respective electric wire in a respective wire hole in the plug body, each terminal slot having a broad bottom positioning section, a narrow top engagement section, a middle section connected between the bottom positioning section and the top engagement section, the middle section having a diameter smaller than the bottom positioning section but greater than the top engagement section, and a sloping guide section connected between the middle section and the top engagement section and sloping upwardly inwards from the middle section toward the top engagement section, the terminals each having a mounting base fitting the contour of the corresponding terminal slot and two hooked positioning portions forced into engagement with the peripheral wall of the bottom positioning section of the corresponding terminal slot.