A power source for control equipment which is designed so that even if one or more independent power sources (700) are added to a main power source (600), the power source arrangement, as viewed from the control equipment supplied with power therefrom, can always be regarded as if one power source were connected thereto. The operative state of control circuit power sources (601, 701) provided in the main power source (600) and the additional power source (700) is detected by control circuit power source abnormality detecting circuits (603, 703), and the operative state of driving power sources (602, 702) provided in the main power source (600) and the additional power source (700) is detected by driving power source abnormality detecting circuits (604, 704). All the driving power sources (602, 702) are turned ON substantially concurrently after the outputs from all the control circuit power sources (601, 701) have reached their normal state, and they are turned OFF substantially concurrently when the output from any one of the control circuit power sources (601, 701) has become abnormal. An enable signal (EN), which is sent to the control equipment, is turned ON after all the control circuit power sources (601, 701) and driving power sources (602, 702) have reached their normal operative state, and is turned OFF when an abnormality has occurred in any one of the power sources.