A fine particle measurement device includes a support stand (20) that has a groove (F) extending in a predetermined direction and is configured to support in the groove an observation container (10), which has an elongate shape and accommodates a liquid sample containing a fine particle therein such that an extending direction of the groove (F) coincides with a longitudinal direction of the observation container (10); and an imaging unit (40) that is configured to capture an image of the fine particle in the observation container (10) at a position where the support stand is out of a field of view, the observation container (10) being supported by the support stand (20).