A particle imaging device comprises a flow cell, a light source, an irradiation optical system configured to form a light sheet on the flow cell, a light collecting optical system and an imaging element. The sheet surface of the light sheet is perpendicular to the exterior side surface of the flow cell to which the light is entered from the light source. The sheet surface of the light sheet is inclined at a predetermined angle that is not perpendicular to the flow direction of the sample.