In a liquid medicine injecting system, an open route is formed in which a liquid medicine flows from a container that contains the liquid medicine to a blood vessel of a biological body via a micro-pump, a flow volume sensor, and a tube. A back pressure from the biological body directly operates against the micro-pump via the open route. When the flow volume of the liquid medicine is constant, power of the micro-pump has a constant relationship with the back pressure. The flow volume of the liquid medicine is adjusted to be a target volume by controlling the power of the micro-pump, and the power of the micro-motor is monitored. An abnormal injecting state of the liquid medicine caused by such as pulling out of an injection needle from the biological body is immediately detected with high accuracy based on the monitored result of the power of the micro-pump.
