An electric current supply control apparatus for a glow plug, and glow plug and the electric current supply control apparatus connected to the glow plug. In a transition state in which the load acting on an engine increases such as at the time of acceleration (S14: YES), an instruction signal which instructs increasing of an EGR amount is transmitted to an ECU (S18). Further, electric current is supplied to a heat generation resistor of a glow plug through resistance PI control (S20), whereby the temperature of the heat generation resistor is stably maintained at a target temperature, and stability of combustion is enhanced. Thus, even at the time of acceleration, generation of NOX can be suppressed effectively by increasing the EGR amount without lowering the engine output.