PURPOSE: To facilitate thrusting of a capillary into cells in injecting a DNA, etc., by applying an AC voltage, forming a pearl chain composed of cells, then rotating the cells by a change in frequency and arranging the cells at desired positions.

CONSTITUTION: A solution containing cells is initially introduced into a space between opposite electrodes 20 and an AC voltage is then applied across the opposite electrodes 20 to form a pearl chain composed of the aforementioned cells 26. The AC frequency of an AC power source 25 is then changed to rotate the cells 26. Desired sites of the cells to be treated are subsequently arranged at desired positions. An injection capillary 16 is then thrusted into the above- mentioned desired sites.