In an automatic transmission, the control part controls the engaging mechanisms and recognizes the rotational speed of a drive source and a stop request for the drive source. The automatic transmission changes the rotational speed of the input member to transmission gear ratios by the planetary gear mechanism and the engaging mechanisms so as to freely output the rotation from the output member. The engaging mechanisms include a switching mechanism switchable between a fixed state and a reverse rotation preventing state in which a normal rotation of a corresponding element among the elements of the planetary gear mechanism is allowed and a reverse rotation thereof is prevented. The control part switches the switching mechanism in a state in which the stop request for the drive source is not recognized and the rotational speed of the drive source is equal to or greater than a predetermined value.

When an input torque becomes greater by a predetermined value or more due to an operation of increasing an amount of accelerator depression amount or the like during a gear shift, a controller for an automatic transmission updates a target gear shift characteristic value to a target gear shift characteristic value which is set when the gear shift is started with the input torque based on the input torque at the updating time, and performs gear shift control from a degree of progress in gear shift at the updating time based on the updated target gear shift characteristic value. Since the target gear shift characteristic value can be changed with respect to an increase in the input torque during the gear shift by this control, it is possible to prevent a decrease in durability of frictional engagement elements.

In an automatic transmission, the control part controls the engaging mechanisms and recognizes the rotational speed of a drive source and a stop request for the drive source. The automatic transmission changes the rotational speed of the input member to transmission gear ratios by the planetary gear mechanism and the engaging mechanisms so as to freely output the rotation from the output member. The engaging mechanisms include a switching mechanism switchable between a fixed state and a reverse rotation preventing state in which a normal rotation of a corresponding element among the elements of the planetary gear mechanism is allowed and a reverse rotation thereof is prevented. The control part switches the switching mechanism in a state in which the stop request for the drive source is not recognized and the rotational speed of the drive source is equal to or greater than a predetermined value.

When an input torque becomes greater by a predetermined value or more due to an operation of increasing an amount of accelerator depression amount or the like during a gear shift, a controller for an automatic transmission updates a target gear shift characteristic value to a target gear shift characteristic value which is set when the gear shift is started with the input torque based on the input torque at the updating time, and performs gear shift control from a degree of progress in gear shift at the updating time based on the updated target gear shift characteristic value. Since the target gear shift characteristic value can be changed with respect to an increase in the input torque during the gear shift by this control, it is possible to prevent a decrease in durability of frictional engagement elements.