PURPOSE: To provide a simulation apparatus able to test a combined sensing-type seeker.

CONSTITUTION: Antenna horns 2, 3, 4 belonging to the same antenna horn group radiate the electromagnetic wave with the same frequency, antenna horns 2, 3, 4 belonging to the different antenna horn groups radiate different electromagnetic waves respectively, an infrared ray target generating apparatus 5 put in the center of an antenna array 1 and infrared ray background apparatus 5a put in radiately radiate infrared-rays, and the radiation intensity of respective electromagnetic waves and infrared-rays is controlled by a target background computing apparatus, so that the target and the background can be simulated by electromagnetic waves with a plurality of frequencies and infrared rays and as a result an apparatus which enables a combined sensing-type seeker to be tested is obtained.