PURPOSE: To obtain a vent-type upright injection apparatus that gives rise to no vent up and thus has an excellent vent effect by boring an vent hole slanting ly upward on the wall of a heating cylinder having a screw housed therein and installed vertically with respect to a mold clamping device, and defining a gas communication interstice between the rear end of the screw and the heating cylinder.

CONSTITUTION: A heating cylinder 1 is longitudinally installed with respect to an upright mold clamping device 7. On the wall of a melting part in the heating cylinder 1, a vent hole 5 is slantingly provided toward the counter-nozzle direction to the axis of the heating cylinder 1 and a gas communication interstice 6 is defined between the screw rear end 2a and the heating cylinder rear end 1a. As a consequence of this manner, this will bring about no vent up in comparison with a horizontal type injection device, and also, the discharged of produced gas is executed smoother than in the case that such vent hole 5 is provided with respect to the axis of the heating cylinder 1.