To improve the image pickup efficiency without performing an meaningless image pickup by detecting that a particle crosses the light from a trigger light source, generating an image pickup pulse beam on the basis of the generated particle detecting signal, and analyzing the static image of the particle by the pulse beam.
The light emitted from an image pickup laser pulse beam source 20 is throttled by a condenser 22, and the light transmitted by a flow cell 18 reaches an objective lens 24. When the cell in a liquid sample passes an image pickup point 38 when the pulse beam is emitted, the whole image of the cell is taken by a CCD camera 26. This image is transmitted to a static image input part 28, subjected to image processing by an image analyzing part 30, and analyzed. A trigger light source 32 of semiconductor laser is regularly lighted, the cell detection signal detected in the flow cell 18 by a cell detector 34 is delayed for a fixed time by a delay circuit 36 to light the light source 20, and the cell is photographed.