Disclosed is a control device for a hybrid vehicle having an engine (1) and a motor generator (2) connected via a first clutch (4). In an EV mode in which the first clutch (4) should be in a released state, a diagnosis of the first clutch (4) is executed. An air conditioner (41) is provided in the hybrid vehicle such that a compressor (42) of the air conditioner is driven by the engine (1). An HEV mode is thus selected during operation of the air conditioner (41). When the hybrid vehicle has run at a predetermined speed or higher for a predetermined time, the diagnosis of the first clutch (4) is executed upon temporarily switching the running mode to the EV mode in a stop state of the hybrid vehicle.