A first conductor and a second conductor are provided at a diaphragm. The first and second conductors intersect magnetic force lines between north poles and south poles of permanent magnets M which are adjacent to one another. When electricity passes through the conductors, a direction in which a force from the magnetic field acts on the current is substantially orthogonal to a surface of the diaphragm. Therefore, the diaphragm can be oscillated in the direction orthogonal to the diaphragm surface. The conductors have widths of from 1000 m to 2000 m. Therefore, relative errors in the widths caused by etching can be greatly reduced compared to the prior art, and etching is easier. Moreover, the conductors are arranged in a zigzag pattern. Because the conductors do not have a coil form, a large number of through-holes is not required as in conventional products.