An angle adjusting mechanism for a mouthpiece bearing portion of a telephone includes a hinge, a guiding member, a connecting member, a pushing member, a first wheel, and a second wheel. The hinge and the guiding member are fixed on opposite ends of the connecting member. The first wheel is fixed on the pushing member, and the second wheel is fixed on the mouthpiece bearing portion. The first wheel and the second wheel engage together and an end of the pushing member is connected to the guiding member. The hinge can rotate to slide the pushing member to rotate the first wheel. The second wheel turns to achieve a constant angle for the handset bed even if main body of telephone is propped up to an angle from a supporting surface.