A volume measuring apparatus is provided with: an acoustic tube whose one end is communicated with a container in which an object to be measured is contained; another container communicated with the other end of the acoustic tube; a partition chamber which defines a sealed space disposed adjacent to the another container and which includes a partition plate for dividing the sealed space and an inner space of the another container; and an electromotive-type speaker which is disposed in the sealed space and whose acoustic wave output surface is disposed opposite to the partition plate. A processing device obtains a volume of the object to be measured, on the basis of an acoustic signal associated with an acoustic wave outputted into the another container via the partition plate from the acoustic wave output surface.