PURPOSE: To ensure appropriate engine braking without degrading drivability by engaging the lockup clutch of an automatic transmission only when it is judged that the level of requirement for braking is large based on the number of braking or the total time period of braking in a predetermined time period.

CONSTITUTION: The lockup clutch controller of an automatic transmission for vehicle is formed so that the lockup clutch of an automatic transmission is engaged at the time of applying brake for a vehicle. The number of braking in a predetermined time period or the total time period of braking in a predetermined time period is detected by a detection means. It is judged whether the requirement for braking is large or not by a judgement means based on at least the detection value of either detection means. Only when the requirement for braking is judged to be large, the lockup clutch is engaged by an engagement means. Appropriate effect of engine brake is ensured only when it is required without degrading drivability, in particular accommodation during traveling.