The present invention is to present a cell analyzer capable of measuring cells which are approximately 20 to 100 μm in size with high precision via flow cytometry. The cell analyzer 10 comprises: a flow cell 51 in which a measurement sample including a measurement target cell flows; a light source part 53 for irradiating a light on the measurement sample flowing in the flow cell 51; an optical system 52 for forming a beam spot on the measurement sample flowing in the flow cell 51, the beam spot having a diameter of 3˜8 μm in a flow direction of the measurement sample and a diameter of 300˜600 μm in a direction perpendicular to the flow direction of the measurement sample; and a light receiving part 55, 58, 59 for receiving a light from the measurement sample.