Abstract: A power adapter has a main body. A top of the main body defines a recess and an annular sidewall enclosing the recess. The recess has a locating depression arranged at a bottom thereof to be deviated from the center of the bottom. A plug is rotatably and detachably mounted in the recess. An elastic component mounted in the plug defines a contacting portion elastically protruding out of a bottom of the plug. The plug is locked in the recess by rotation so that the contacting portion is pressed against the bottom surface of the recess and compressed back elastically and then the contacting portion engages the locating depression under resilience action of the elastic component for preventing the plug from rotating with respect to the main body.