A method and apparatus for locating an abnormality in a gas-insulated electric device, operative to locate the spot of an insulation abnormality, which emerges inside a metallic container, from outside of said metallic container. A plurality of detectors (S.sub.0 -S.sub.n) disposed at certain positions in the metallic container produce detected signals, from which spectrum strengths (YH) in a high frequency band of 500 MHz or above are evaluated, and a position which renders a maximum spectrum strength is calculated from the relation between the spectrum strengths and the installation positions of the detectors and is determined to be the spot (x) of partial discharge.