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.

An automatic analyzer includes an installation plate on which a system reagent container is installed, a liquid aspiration unit that aspirates a reagent from the system reagent container, a support unit to which the liquid aspiration unit is coupled and which can be moved between a reagent container exchange position and a reagent aspiration position, and a lift mechanism that allows the support unit to perform a lift operation. The support unit of the liquid aspiration unit is raised to the reagent container exchange position by the lift mechanism when a first condition is satisfied, and the support unit of the liquid aspiration unit is lowered to the reagent aspiration position by the lift mechanism when a second condition is satisfied.