Abstract: A power supply adapter includes a casing defining at least one inserting groove therein, at least one resilient piece disposed in the casing and having a locating portion and a resisting portion extended gradually upward from the locating portion, and a plug module rotatablely disposed in the casing. The plug module has at least one retaining block disposed in the inserting groove of the casing and capable of rotating around the resisting portion of the resilient piece. A connecting terminal runs through the retaining block to form an inserting portion and a projecting portion at opposite sides of the retaining block. The projecting portion is capable of compressing the resisting portion when the inserting portion is raised erectly to be exposed externally from the inserting groove.