To provide a speaker which suppresses a rise in temperature of a voice coil by efficiently cooling the voice coil, has high input resistance and large output, and outputs stable sound pressure.

The speaker has a magnetic circuit which has a magnet 18 disposed between an upper plate 20 and a lower plate 12 of magnetic bodies and is formed through a center pole 14 extending from the center of the lower plate 12. Further, the speaker has an annular magnetic gap 24 formed between the center pole 14 and upper plate 12, a frame 26 fixed onto the top surface of the upper plate 20, and a bobbin 30 which has a plurality of air vents 40 for ventilation along a cylinder axis formed inside a cylinder wall and also has a recessed part 36 peripherally outside to the whole periphery. The speaker has the voice coil 38 wound around the recessed part 36 of the bobbin 30 and disposed in the magnetic gap 24 and a diaphragm 28 which has its external edge part fixed to the peripheral edge of the frame 26 and where the bobbin 30 is coupled at its center part, and the bobbin 30 vibrates in the magnetic gap 24 along the cylinder axis.