A fixation device comprising: a fixation member configured to include a heating member; a pressure-application member configured to press-contact the fixation member to form a nip portion therebetween; an exciting coil configured to induction-heat the heating member of the fixation member; a first temperature detection unit configured to detect a first temperature of the pressure-application member; a second temperature detection unit configured to detect a second temperature of the fixation member; a third temperature detection unit configured to detect an ambient temperature in the neighborhood of the fixation member; a control unit configured to select one of a temperature control mode and a power control mode to control electric power supplied to the exciting coil; and an IH (induction heating) control unit supplying electric power to the exciting coil; wherein the control unit, upon receiving a signal indicating that current has been applied to the exciting coil, determines that a heat storing state of the fixation device is a cold state when the first temperature of the pressure-application member detected by the first temperature detection unit is equal to or lower than a first threshold temperature, determines that the heat storing state of the fixation device is a warm state when the first temperature of the pressure-application member is higher than the first threshold temperature, and the ambient temperature in the neighborhood of the fixation member detected by the third temperature detection unit is equal to or lower than an ambient threshold temperature, and determines that the heat storing state of the fixation device is a hot state when the first temperature of the pressure-application member is higher than the first threshold temperature, and the ambient temperature in the neighborhood of the fixation member is higher than the ambient threshold temperature, wherein the control unit controls electric power supplied to the exciting coil, by selecting the power control mode when the heat storing state of the fixation device is the cold state or the warm state, to continuously supply a predetermined level of the electric power to the exciting coil, or by selecting the temperature control mode when the heat storing state of the fixation device is the hot state, without transitioning to the power control mode, to supply the electric power determined based on the second temperature of the fixation member detected by the second temperature detection unit, to the exciting coil, wherein a reference temperature for transitioning from the power control mode to the temperature control mode, and a target temperature of the fixation device in the temperature control mode are set for the second temperature of the fixation member detected by the second temperature detection unit. a fixation member configured to include a heating member; a pressure-application member configured to press-contact the fixation member to form a nip portion therebetween; an exciting coil configured to induction-heat the heating member of the fixation member; a first temperature detection unit configured to detect a first temperature of the pressure-application member; a second temperature detection unit configured to detect a second temperature of the fixation member; a third temperature detection unit configured to detect an ambient temperature in the neighborhood of the fixation member; a control unit configured to select one of a temperature control mode and a power control mode to control electric power supplied to the exciting coil; and an IH (induction heating) control unit supplying electric power to the exciting coil; wherein the control unit, upon receiving a signal indicating that current has been applied to the exciting coil, determines that a heat storing state of the fixation device is a cold state when the first temperature of the pressure-application member detected by the first temperature detection unit is equal to or lower than a first threshold temperature, determines that the heat storing state of the fixation device is a warm state when the first temperature of the pressure-application member is higher than the first threshold temperature, and the ambient temperature in the neighborhood of the fixation member detected by the third temperature detection unit is equal to or lower than an ambient threshold temperature, and determines that the heat storing state of the fixation device is a hot state when the first temperature of the pressure-application member is higher than the first threshold temperature, and the ambient temperature in the neighborhood of the fixation member is higher than the ambient threshold temperature, wherein the control unit controls electric power supplied to the exciting coil, by selecting the power control mode when the heat storing state of the fixation device is the cold state or the warm state, to continuously supply a predetermined level of the electric power to the exciting coil, or by selecting the temperature control mode when the heat storing state of the fixation device is the hot state, without transitioning to the power control mode, to supply the electric power determined based on the second temperature of the fixation member detected by the second temperature detection unit, to the exciting coil, wherein a reference temperature for transitioning from the power control mode to the temperature control mode, and a target temperature of the fixation device in the temperature control mode are set for the second temperature of the fixation member detected by the second temperature detection unit.