Electrical component box for an air conditioner and an air conditioner equipped with the same

The electrical component box for an air conditioner having a compressor and a blower fan, a first control board heat generating component is mounted, the upper portion of the first partition plate holding the control board dividing the blowing fan and compressor a first substrate holder to be installed, and a second control board mounted in a substantially vertical or substantially horizontal to the first control board non-heat generating component is mounted, the second to hold the second control substrate a substrate holder, and a radiation fin projecting blower fan side of the mounted partition plate to the first control board is provided.