The purpose of this study was to investigate effect of electrical noise on malfunction of the earth leakage circuit breaker. A three-way experiment for studying its malfunction was conducted, in which electrical products such as radio, alternating current arc welder and cellular phone, distance from the earth leakage breaker to electrical products, and whether or not the earth leakage breaker is contained in the steel box were employed as experimental variables. Eleven earth leakage breakers frequently used in real situations were tested in each experimental treatment. The electrical products were used for generating electrical noise that is known to be able to cause malfunction of the earth leakage breaker. The results showed that except a case for one of the 11 earth leakage breakers when the radio made by M company was located 30 cm ahead of the breaker, malfunction did not occur in any other experimental treatment. Consequently, it is suggested that the breaker should be normally used for preventing electricity-related accidents without fear of its malfunction in industrial sites.