During metering, a screw is retreated to a preset metering completion position while it is being forwardly rotated. Pilot injection is performed such that the screw is reversely rotated and advanced so that a resin pressure reaches a predetermined compression pressure, during a time period between the end of the metering and the start of injection. The screw reverse rotation is continued before the screw advance is started for the pilot injection. In this way, a check valve can be closed at a relatively low pressure such that precision metering can be achieved.