In a case of an electric failure caused to a traveling vehicle and when any of forward gears is held at a step S5, a comparison is made between: 1) a supposedly-engaged friction element of friction elements which is supposed to be engaged at the any of the forward gears and 2) an actually-engaged friction element of the friction elements which is sensed to be actually engaged, the sensing being based on a switch signal from a first hydraulic pressure switch 11, a second hydraulic pressure switch 12, a third hydraulic pressure switch 13, a fourth hydraulic pressure switch 14 and a fifth hydraulic pressure switch 15. When the supposedly-engaged friction element is not in accordance with the actually-engaged friction element, an electric system is determined to be in failure. In the case of the electric failure, a routine moves to a step S6 and subsequent steps for sticking the gear of an automatic transmission to a given gear. As described above, a shift control system of the automatic transmission is thus provided that can eliminate a sleeping failure thereby securely preventing an interlock and that can secure a high shift controllability which is not, in a period of shift, restricted in terms of hydraulic pressure control range of each of the friction elements.