To solve the problem of a control apparatus for controlling the number of operating generators in cogeneration power generating facility that a reverse power is generated from the generator if delivery of a generator stop command is delayed when the load decreases abruptly immediately after automatic closing of the generator.

A receiving power decision section makes a decision whether a receiving power is equal to or lower than a constant level and a stop signal is delivered to a generator through the decision section, a stop power decision section, and a timer set with a time limit of several seconds by the AND signal of 52G closing and an automatic operation signal.