CONTROL DEVICE OF AUTOMATIC TRANSMISSION

A control device of an automatic transmission to set and control a gear position based on a vehicle speed and an accelerator opening degree, includes a controller determining a high load travel based on a travel resistance during travel control on a gear shift line, which is set such that a region on a higher accelerator opening degree side of a downshift line is a region where a lock-up clutch is to be turned off, and turning off the lock-up clutch before downshifting when determining the high load travel.