A miniature speaker is disclosed. The miniature speaker includes a frame providing a receiving space, a magnetic circuit positioned in the receiving space and a vibration unit including a diaphragm and a voice coil driving the diaphragm. The magnetic circuit includes a main magnet positioned on a center of the lower plate, a pair of auxiliary magnets positioned spaced from the main magnet for forming a magnetic gap, a pole plate attaching to a top surface of the main magnet, and an upper plate. The upper plate includes a pair of main segments attached to top surfaces of the auxiliary magnets, and a pair of connecting beams connecting with the main segments and located between the two auxiliary magnets. The magnets are prevent from being attracted to each other by virtue of the upper plate.