A micro-speaker includes a case having a ring wall forming a receiving cavity, a number of restricting apertures formed in the ring wall, a magnetic plate received in the case and having a main plate, a plurality of auxiliary plates extending from the main plate, and a number of protrusions extending from edges of the auxiliary plates, a first gap formed between two adjacent auxiliary plates communicating with the receiving cavity of the case, the main plate and the auxiliary plates being surrounded by the ring wall of the case, and the protrusions being located in the restricting apertures for restricting the magnetic plate in proper position.