Liquid surface position detection device

A liquid-surface position detection device includes: a propagation body being disposed in a container immersed in a liquid and propagating surface waves; a vibration generation and detection means imparting vibrations to the propagation body and including a piezoelectric element detecting reflected surface waves; and a position detection means calculating the liquid surface position from the reflection time of the surface waves. The propagation body is made of a resin material and provided integrally, at the upper part thereof, with an element accommodating part which accommodates the piezoelectric element. The element accommodating part includes a bottom surface section formed so that a portion thereof juts out from a main surface forming the surface of the propagation body. The piezoelectric element is disposed so that a portion thereof juts out from the main surface, and to apply vibrations to the main surface in the vertical direction via the bottom surface section.