A large number of micro bubbles are generated by injection of a pulsed power (0.41 MW, 1 µs [FWHM]) into water solution with 5.7-wt% sodium hydrogen carbonate (NaHCO₃) as an additive. The diameter of the bubbles is estimated to be 23 µm which is half of that obtained without the additive. The number density of the bubbles with the additive is 6 times as high as that obtained without the additive. We found that 98 % of the larva of Artemia (brine shrimp) are successfully inactivated by firing 800 injections of pulsed power into water solution with the additive, which is 1.6 times as high as that obtained for the water solution without the additive. The gross energy efficiency for inactivation reaches 0.25 million larvae a kWh. It indicates that a large number of micro bubbles generated by the injection of pulsed power are effective to inactivate the zooplankton in the water.