PURPOSE: To make it possible to perform the optimum transmission control responsively to all of transmission elements, such as temperature of an engine, load of the engine, and others, by deciding the end of the transmission according to the rotating speed on the input side of a transmission gear mechanism, in an automatic transmission.

CONSTITUTION: This automatic transmission is formed with a torque converter 2 connected to an output shaft 1 of an engine, and a transmission gear mechanism 10 set on the output side of said torque converter 2. Moreover, this automatic transmission is formed with a turbine sensor 201 adapted to detect the rotating speed on the input side of the transmission gear mechanism 10, and a controller 200 adapted to decide the end of the transmission according to variety of the rotating speed through accepting the output of the turbine sensor 201, and perform setting of a transmission stage on which engine brake is not effected. That is, turbine rotating speed is measured by the turbine sensor 201, and it is decided whether the measured rotating speed is lowered under preset value or not, on the base of the transmission start time, by the controller 200. When the turbine rotating speed is lowered under the preset value, if the variation ration of the turbine rotating speed is lower than the present value, the end of transmission is decided.