A gear shift control device for controlling a hybrid vehicle drive system (1) including an automatic transmission (3), a clutch (4), a clutch actuation mechanism (48), and a motor (5), includes a torque indication means for indicating a driver request torque (Tdrv) determined by an operation amount of an acceleration means, a gear shift control means for, when a gear shift condition is fulfilled, reducing an engine torque (Te) and generating a motor torque (Tm), for bringing the clutch (4) in a disconnected state, for, after changing a selection of gear sets of a gear train (33), returning the clutch (4) to a connected state, and for reducing the motor torque (Tm) and increasing the engine torque (Te), and a motor torque computing means for, after changing the selection of the gear sets of the gear train (33), computing the motor torque (Tm) on the basis of a first subtraction value (Tm1) obtained by subtracting a clutch torque (Tc) from the driver request torque (Tdrv).