To prevent a false notification of the weight of a container containing an infusion fluid to be infused into a patient from being generated when the container is detached.

When it is determined that the weight of the container containing the infusion liquid detected by a weight sensor 1 reaches a weight at the time of finish of drip infusion, time measurement starts. If a controller 2 determines that the weight detected with the weight sensor 1 has become zero before the measured time reaches a predetermined time, it is determined that the container is detached from the weight sensor 1, and the controller 2 does not output a notification signal for causing operation of the notification device 3 to the notification device 3. When the controller 2 determines that the weight detected by the weight sensor 1 has not become zero before the measured time reaches the predetermined time, it is determined that the container is not detached from the weight sensor 1 and that the time of finish of infusion drip has come, and the controller 2 outputs a notification signal to the notification device 3.