PURPOSE: To perform drip control in which a drip condition can be prevented from being fluctuated by the degree of skill of a person who treats drip setting and with high reproducibility and stability by employing such constitution that an ultrasonic sensor incorporating an ultrasonic transmission element and an ultrasonic reception element is embedded in the bottle wall of a drip bottle.

CONSTITUTION: The ultrasonic sensor 7 is embedded on the side of the delivery port 2 of the bottle wall 6 parallel with a medicinal liquid face L on the lower terminal of the drip bottle 1. The sensor 7 is unified by enclosing the ultrasonic transmission element 7a which radiates an ultrasonic pulse on medical liquid A in the drip bottle 1 and the ultrasonic reception on element 7b which outputs an electrical signal by receiving the ultrasonic pulse reflected from the liquid face L of a medicinal liquid A by a prescribed exterior material 7c. Two kinds of timing signals from an ultrasonic receiver 10 are outputted with time difference proportional to distance between the sensor 7 changing based on the increment/decrement of medicinal liquid quantity in the drip bottle 1 and the liquid face L.