Injection device and injection control method

An injection device, comprising:

• an injection cylinder which accumulates a molding material and has an injection nozzle at the front;
• an injection plunger which is moved backward in the injection cylinder;
• an injection plunger driving device which moves the injection plunger backward;
• an injection controller;
• a position detection device which detects a position of the injection plunger;
• and
• a pressure detection device for detecting a resin pressure of the molding material in the injection cylinder, wherein
• the injection controller is configured to calculate a retreat speed of the injection plunger in a plastication metering step of an n-th injection cycle from a metering time of the injection plunger measured by the position detection device in a plastication metering step of an (n-1)-th injection cycle, and the injection controller is configured to directly control the injection plunger to retreat based on a value of the resin pressure and the retreat speed to perform metering, before a suck-back step can be omitted, wherein the n is an integer of 3 or more.