Conventionally, a stepped automatic transmission that is mounted in a vehicle, for example, controls the engagement states of a plurality of friction engagement elements (clutches and brakes) by using a hydraulic control apparatus, and enables shifting by establishing power transmission paths in a shift speed gear train for each shift speed. In addition, in recent years, increasing the number of stages of an automatic transmission has become necessary in order to improve the fuel economy of the vehicle, and in such an automatic transmission. In order to select the optional shift speed according to the driver's requirements (that is, the amount of accelerator pedal depression and the like), jump shifting, in which the shift speed shifts to a shift speed that is separated by two or more stages from the original shift speed in one shift is carried out (for example, a 4-2 shift, a 5-2 shift, a 2-4 shift, a 2-5 shift, and the like).
In contrast, anticipating how the driver will operate the accelerator pedal is difficult. For example, in cases in which the driver depresses and then immediately releases the accelerator pedal or releases and then immediately depresses the accelerator pedal, the situation occurs in which it is determined that there should be a next shift during the control in which the control of the clutch shifting of the friction engagement elements is being carried out after it is determined that a shift change should occur. In such a case, when the later shift control is started after waiting until the former shift control has completed, a timing lag occurs with respect to the accelerator pedal operation by the driver. Thus, there is a concern that in the case of, for example, an upshift after a downshift, a sense of dragging caused by engine braking will occur, and there is a concern that in the case of a downshift after an upshift, a sense of delay, in which the required output cannot be obtained, will occur, and this may cause a deterioration in the drivability.
Thus, in order to prevent the occurrence of the timing lag described above, and in order to improve drivability (in particular, to avoid any discomfort due to engine braking), an invention that carries out what is termed as multiple shifting has been proposed (refer to Japanese Patent Application Publication No. JP-A-HEI 11-A-108178). In multiple shifting, when it is determined that a shift should occur during the previous shift control (in particular, in the case in which it is determined that an upshift should occur during a downshift), the previous shift control is suspended, and the next (subsequent) shift control is started while overlapping the previous shift control.