A power generation control apparatus which is to drive a plurality of electric generators including a main electric generator and a subordinate electric generator, which are mounted on one internal combustion engine, at the same time by means of said internal combustion engine, comprising: a first power generation control device (4, 4A) connected to said main electric generator; and a second power generation control device (4, 4A) connected to said subordinate electric generator; wherein said first and second power generation control devices (4, 4A) are each provided with: an external sensing terminal (c) configured to detect an external voltage of a battery; an output sensing terminal (a) configured to detect a power generation voltage generated by said each electric generator itself; a terminal (f) configured to output a field current from the battery to each field coil of said each electric generators, as a field current control signal; and an external output terminal (d) configured to output a signal synchronized with the field current control signal which is obtained by voltage dividing the field current control signal; wherein the power generation voltage of each of said electric generators is regulated to a target voltage value by carrying out field current control using the field current control signal in which a field current is supplied to said each field coil, wherein the field current control signal is an intermittent on/off signal; and wherein when said plurality of electric generators are caused to drive at the same time, the external output terminal (d) of said first power generation control device (4, 4A) and the external sensing terminal (c) of said second power generation control device (4, 4A) are connected to each other. a first power generation control device (4, 4A) connected to said main electric generator; and a second power generation control device (4, 4A) connected to said subordinate electric generator; wherein said first and second power generation control devices (4, 4A) are each provided with: an external sensing terminal (c) configured to detect an external voltage of a battery; an output sensing terminal (a) configured to detect a power generation voltage generated by said each electric generator itself; a terminal (f) configured to output a field current from the battery to each field coil of said each electric generators, as a field current control signal; and an external output terminal (d) configured to output a signal synchronized with the field current control signal which is obtained by voltage dividing the field current control signal; wherein the power generation voltage of each of said electric generators is regulated to a target voltage value by carrying out field current control using the field current control signal in which a field current is supplied to said each field coil, wherein the field current control signal is an intermittent on/off signal; and wherein when said plurality of electric generators are caused to drive at the same time, the external output terminal (d) of said first power generation control device (4, 4A) and the external sensing terminal (c) of said second power generation control device (4, 4A) are connected to each other. an external sensing terminal (c) configured to detect an external voltage of a battery; an output sensing terminal (a) configured to detect a power generation voltage generated by said each electric generator itself; a terminal (f) configured to output a field current from the battery to each field coil of said each electric generators, as a field current control signal; and an external output terminal (d) configured to output a signal synchronized with the field current control signal which is obtained by voltage dividing the field current control signal; wherein the power generation voltage of each of said electric generators is regulated to a target voltage value by carrying out field current control using the field current control signal in which a field current is supplied to said each field coil, wherein the field current control signal is an intermittent on/off signal; and wherein when said plurality of electric generators are caused to drive at the same time, the external output terminal (d) of said first power generation control device (4, 4A) and the external sensing terminal (c) of said second power generation control device (4, 4A) are connected to each other.