Abstract: To provide an automatic analyzer with improved workability when a flow cell is loaded and unloaded. The automatic analyzer includes: a photomultiplier tube; a board disposed vertically below the photomultiplier tube; and a flow cell disposed vertically below the board. A lower surface of the board has a protrusion portion and/or a recess portion, and an upper surface of the flow cell has a recess portion and/or a protrusion portion. The automatic analyzer includes a pressing member configured to press the flow cell vertically upward from below in a state in which the recess portion and/or the protrusion portion of the flow cell is fitted to the protrusion portion and/or the recess portion of the board.