The present invention relates to an injection molding machine, which comprises an L-shaped main body frame, a fixed rod a, a fixed rod b, a power supply connection port and a conducting wire, wherein the fixed rod a is fixed on the left arm of the L-shaped main body frame, the bottom portion of the L-shaped main body frame is provided with a cylindrical mold, the top end of the cylindrical mold is connected with the fixed rod a, the bottom end of the cylindrical mold is connected with the bottom portion of the L-shaped main body frame through the fixed rod b, the top portion of the cylindrical mold and the top portion of the L-shaped main body frame are connected with a material inlet, the left bottom end of the L-shaped main body frame is provided with the power supply connection port, the bottom portion of the cylindrical mold is provided with a flatness detection device, and the flatness detection device and the power supply connection port are connected through the conducting wire. The injection molding machine of the present invention has beneficial effects of simple structure, low production cost, and effective product quality improving.