A control device for an automatic transmission having a torque converter includes: a determining means for determining whether to set a friction element in an engaged condition or a disengaged condition on the basis of an operating condition of a vehicle; a control means for outputting an engagement command or a disengagement command on the basis of a determination result of the determining means; and an oil pressure control means for performing control to engage the friction element upon reception of the engagement command by performing a precharge control for the friction element and then controlling the supplied oil pressure to a predetermined oil pressure and to disengage the friction element upon reception of the disengagement command by draining the oil pressure supplied to the friction element, wherein the control means comprises a prohibiting means for prohibiting output of the disengagement command in relation to the friction element following control of the friction element from the disengaged condition to the engaged condition until a predetermined condition is established.