PURPOSE: To measure the amount of storage with high accuracy by issuing an ultrasonic wave to the upper face of a stored material from ultrasonic sensors that are arranged radially at the upper section of a silo and are able to go up and down.

CONSTITUTION: A wire 6 goes up and down by means of a wire winding and unwinding device 5, and ultrasonic level sensors 3 hang at a specified position measurement elements that are arranged radially. The distance of the up and down movement of the wire 6 is detected by a movement distance detector 8. An ultrasonic wave is oscillated from an ultrasonic level sensor 3. The measuring points that correspond to the sensors 3 that cover all the upper face of a stored matter 7 are detected by detecting the reflection wave. The distance signal of each measuring point and the movement distance signal for the movement of the wire 6 are input to a store volume measurement device 9 and the input is processed there for calculation to calculate the volume of the stored matter from the shape of the upper surface of the stored matter 7 and its distance from the bottom face of the slab 2. With this arrangement the volume of the stored matter can be measured with high accuracy.