The present invention discloses a speaker having a frame, a vibrating system and a magnet circuit system. The vibrating system has a vibrating diaphragm, a voice coil, and an elastic supporting. The magnetic circuit system has a main magnet, as secondary magnet located and spaced on two opposite sides of the main magnet, and a magnetic plate stacked on the secondary magnet and spaced away from the elastic supporting assembly. The magnetic plate includes a main body stacked on the secondary magnet and an extending wall extending from two opposite sides of the main body towards the main magnet and spaced away from the voice coil. The extending wall is facing and spaced away from the elastic supporting assembly. The speaker of the present invention has an excellent acoustic performance.