Disclosed is a micro-speaker. A micro-speaker includes a frame, a magnetic circuit unit accommodating in the frame, a vibrating unit, an assistant coil attached to the frame and disposed below the diaphragm. The vibrating unit includes a diaphragm and a voice coil driving the diaphragm. The assistant coil includes an upper surface facing the diaphragm and an inclined surface connecting the upper surface and disposed closer to the voice coil than the upper surface.