Although disposable cells and high voltage are used for electroporators, a new type of electroporator, for which a permanently reusable cell and low voltage can be used, was manufactured from Korea Biotech. Inc. We wanted to optimize the procedures of electroporation for Escherichia coli using this electroporator. The effects on the electroporation of electric field strength, pulse length, sizes of plasmid, host strains, washing solutions and times, and growth media were studied. Maximum transformation efficiency with E. coli strain CC118 was obtained at the combination of electric field strength of 12.14-12.85 kv/cm and retention time of 4-5 msec. Although the number of transformants was not proportional to the amount of plasmid DNA, larger amount of DNA up to 2μg gave higher number of transformants (109). The highest number of transformants were obtained using cells harvested at 0.6-0.8 of OD600. Ten percent glycerol out of 4 washing solutions, 2 times washing, and SOC medium out of 5 growth media were best for highest efficiencies of transformation. The number of transformants was routinely over 109. Jetgene electroporator seems adequate for electroporation in spite of lower price and working cost.