PURPOSE: To decrease the number of the component parts and then to increase the detection efficiency of the detection signal by setting the center axial line of the signal detection coil of the speaker vertically to the center axial line of the voice coil and also located nearly on the center line of the voice coil which is not within the plane of the voice coil.

CONSTITUTION: Detection coil 14, which detects the vibration of diaphragm 9 and then extracts the motional feedback detection signal, is provided to form the motional feedback speaker. Voice coil 8 of the speaker is installed near the driving yoke at the outer circumference end part of cylindrical body 10 fixed at the center of diaphragm 9, and the center axis Y8 is set in the same direction as center axis Y9 of diaphragm 9. At the same time, oblong and ring-shaped detection coil 14 containing conducting parts 14a∼14d is fixed on the back of cap 15 of supporter 16 on magnetic circuit 12 and supported at the center of body 10. Furthermore, center axial line X of the ring of parts 14a∼14d is set vertically to axis Y8 of coil 8. In such way, the number of component parts can be decreased, also increasing the detection efficiency of the detection signal.