Automatic transmission, control method for automatic transmission, and non-transitory computer-readable medium

[PROBLEMS] When an acceleration request from a driver is large, upshift is performed under a high engine rotation speed.[SOLUTIONS] Provided is an automatic transmission, including: a torque converter that is disposed downstream of a drive source in a power transmission path and is provided with a lockup clutch; and a transmission mechanism that is disposed downstream of the torque converter and changes a speed ratio between an input shaft and an output shaft, in which in a state where the lockup clutch is engaged, when a rotation speed of the input shaft reaches a first rotation speed, the automatic transmission starts upshift, and in a state where the lockup clutch is disengaged or slips, when the rotation speed of the input shaft reaches a second rotation speed obtained by subtracting a first predetermined rotation speed from the first rotation speed, the automatic transmission starts upshift, and the first predetermined rotation speed decreases as an output torque of the drive source increases.