An automatic transmission shift control apparatus is basically provided with deceleration operating condition detecting section, a first shift phase control section and a second shift phase control section. The deceleration operating condition detecting section detects a vehicle coasting condition. The first shift phase control section control a gear ratio of an automatic transmission installed in a vehicle using a first shift phase control after detecting the vehicle coasting condition has started such that a deceleration rate of the vehicle enters a deceleration region. The second shift phase control section control the gear ratio of the automatic transmission after the first shift phase control ends such that the deceleration rate of the vehicle enters a constant speed region.