A circuit board mounting apparatus comprises a chassis and a securing structure. The chassis comprises a bottom board and two sidewalls located on two opposite sides of the board. The securing structure comprises a reinforcing member and a securing member secured to the reinforcing member. The reinforcing member is secured to the bottom board. The securing member defines a securing hole. A fixing member extends through a through hole defined in the circuit board to engage in the securing hole, for preventing the circuit board from moving laterally.