An effect of pulsed electric field treatment on Escherichia coli K-12 suspended in sterilized 1.1g/L NaCI solution was investigated using two types of electrode system, ring-to-cylinder (with and without insulating plate) and spiral electrodes. In ring-to-cylinder electrode system, the microbial inactivation was efficient when the cylinder diameter was small and when insulating plate with a hole was inserted between ring and cylinder electrode. In spiral electrode system, an efficient microbial inactivation was achieved when the wire diameter was 0.90mm.