A synthetic infrared image injection apparatus for simulating images obtained from an electron optics head and injecting them into a signal process part so as to evaluate the performance of an infrared image seeker. The synthetic infrared image injection apparatus comprises: an image input module for receiving the images from a channel synthetic image generation apparatus and extracting an effective area from the received images; a first pixel process module for performing an image process so as to reflect elements influenced by model characteristic effects of the electron optics head in the images; a second pixel process module for realizing dead and hot pixels and an automatic gain; an image transmitting and receiving module for outputting processing images of each module and real-time images before the output thereof formed at least one module among each module; and a system control module for diagnosing and controlling operations of each module.