A method of controlling a dual clutch transmission which includes at least a first input shaft configured to be connected to a first clutch and a second input shaft configured to be connected to a second clutch, and in which a set of odd-numbered gears (Gl, G3, G5) and a set of even-numbered gears (G2, G4, G6) are arranged every one step for alternation respectively between the first and the second input shafts (11, 12) and an output shaft, and in a case of starting transmission of power from a power source to the output shaft, the transmission of the power is started by synchronously engaging a start gear being one of the gears (G1-G6) for start to the second input shaft and connecting the second clutch to the second input shaft, characterized in that the method comprises: calculating an absorbed energy by the second clutch while partially connecting the second clutch to the second input shaft, to which the start gear is synchronously engaged, after starting the transmission of the power from the power source to the output shaft and the first clutch is fully disconnected; detecting an input-rotational-speed Nin of the second clutch, detecting an output-rotational-speed N out of the second clutch, calculating a rotational speed difference ΔN = Nin - N out, if the calculated rotation speed difference of the second clutch is not smaller than a predetermined threshold, update the calculation of the absorbed energy of the second clutch and partially connecting the first clutch to the first input shaft, to which a support gear (SG1, SG3) is synchronously engaged, while keeping the second clutch partially connected, when the updated absorbed energy exceeds a predetermined threshold, the support gear (SG1, SG3) having a gear ratio smaller than that of the start gear by one speed or higher or having a gear ratio greater than that of the start gear by one speed or higher and transmitting torque by both the second clutch and the first clutch; and when the calculated rotation speed difference of the second clutch is smaller than the predetermined threshold fully disconnect the first clutch when the first clutch is not fully disconnected and when the calculated rotation speed difference of the second clutch is smaller than the predetermined threshold fully connecting the second clutch when determining that the first clutch is fully disconnected. calculating an absorbed energy by the second clutch while partially connecting the second clutch to the second input shaft, to which the start gear is synchronously engaged, after starting the transmission of the power from the power source to the output shaft and the first clutch is fully disconnected; detecting an input-rotational-speed Nin of the second clutch, detecting an output-rotational-speed N out of the second clutch, calculating a rotational speed difference ΔN = Nin - N out, if the calculated rotation speed difference of the second clutch is not smaller than a predetermined threshold, update the calculation of the absorbed energy of the second clutch and partially connecting the first clutch to the first input shaft, to which a support gear (SG1, SG3) is synchronously engaged, while keeping the second clutch partially connected, when the updated absorbed energy exceeds a predetermined threshold, the support gear (SG1, SG3) having a gear ratio smaller than that of the start gear by one speed or higher or having a gear ratio greater than that of the start gear by one speed or higher and transmitting torque by both the second clutch and the first clutch; and when the calculated rotation speed difference of the second clutch is smaller than the predetermined threshold fully disconnect the first clutch when the first clutch is not fully disconnected and when the calculated rotation speed difference of the second clutch is smaller than the predetermined threshold fully connecting the second clutch when determining that the first clutch is fully disconnected.