PURPOSE: To make small the peak and dip of the frequency characteristics, to make flat the high frequency sound and to increase the strength of a diaphragm plate, by forming a voice coil to a conductive section through the forming of the conductive part in implanted state, to a diaphragm plate base formed of metal.

CONSTITUTION: A conductive section 2 made of Al as a voice coil in spiral which produces a drive force on the entire surface of a metal made diaphragm plate base 1 is formed in implanting state via an insulation layer 3. In manufacturing this diaphragm plate, an Al layer 12 is formed on a copper-made foil plate 11 with vapor deposition, and the Al layer 12 is provided with a resist layer in spiral, and etching processing is made for the Al 12 to form a conductive section 12a. An insulation layer 12b is formed on the exposed surface of the section 12a through alumite processing, and a beryllium 13 is vapor deposited on the 12a to form the base 1. Finally, the foil plate 11 is removed through etching processing, to form the diaphragm plate with flat high frequency sound.