An apparatus for producing an infrared spectrum according to one example of the present disclosure includes: a toxic chemical gas and background infrared spectrum acquisition portion of acquiring a background of a target area and an infrared spectroscopic signal of a gas contaminant plume existing in the background; and a toxic chemical gas infrared spectrum generation portion of training a Generative Adversarial Network (GAN) using acquired background radiation intensity data as learning data, and automatically generating a toxic chemical gas simulation infrared spectrum signal according to an environment setting inputted from a user using a learned GAN. According to the present disclosure, there is an effect that an infrared spectrum of atmosphere contaminated by a toxic chemical gas may be acquired without outdoor experiments using a real toxic chemical gas.