PURPOSE: To form a small-sized, lightweight speaker excellent in regenerative frequency characteristic and high in followability and efficiency to input signals, by using a high magnetic permeable material on which a magnetizing pattern is recorded, as a diaphragm.

CONSTITUTION: When a signal voltage is applied from an input terminal 44, force from above or below shown by the arrow 45 in the figure is applied to a projected part 32 by interaction of magnetic lines of force with a signal current, i.e. Fleming's left-hand rule, because magnetic lines of force 42 from the magnetizing pattern of the projected part 32 intersects the direction of disposition of a returning wire 33 at right angles. At this time, as the returning wire 33 returns of every magnetizing pattern and the direction of current changes, an upward or downward force is applied to the projected part 32 as a whole. Thus, sound waves corresponding the input signals can be generated by the diaphragm. By this way, a lightweight diaphragm having a large area high in rigidity can be formed by using a material high in magnetic permeability.