A moving object detection apparatus comprising: input means for setting an image capturing parameter for image capturing means; generating means (106, S203, S405, S503) for generating a background model based on a feature of a background region of an image that is captured by the image capturing means; detecting means (107, S204, S404, S504) for detecting at least one moving object region from an image based on the background model; and storing means for storing a background model in association with the set image capturing parameter in a case where an image capturing parameter is set, determining means (106, 108, S206-S207, S407-S408, S506-S507) for determining whether to cause the generating means (106, S203, S405, S503) to newly generate a background model, based on a difference between a first ratio of the area of a detected moving object region relative to the entire first image and a second ratio of the area of the detected moving object region relative to the entire second image, wherein the first image is captured before the image capturing parameter is set and the second image is captured after the image capturing parameter is set, wherein the determining means (106, 108, S206-S207, S407-S408, S506-S507), in a case where the difference is smaller than a threshold, causes the detecting means (107, S204, S404, S504) to continue using the background model without using a new background model, and wherein the determining means (106, 108, S206-S207, S407-S408, S506-S507), in a case where the difference is equal to or greater than the threshold, causes the detecting means (107, S204, S404, S504) to acquire from the storing means a new background model corresponding to the image capturing parameter set via the input means. input means for setting an image capturing parameter for image capturing means; generating means (106, S203, S405, S503) for generating a background model based on a feature of a background region of an image that is captured by the image capturing means; detecting means (107, S204, S404, S504) for detecting at least one moving object region from an image based on the background model; and storing means for storing a background model in association with the set image capturing parameter in a case where an image capturing parameter is set, determining means (106, 108, S206-S207, S407-S408, S506-S507) for determining whether to cause the generating means (106, S203, S405, S503) to newly generate a background model, based on a difference between a first ratio of the area of a detected moving object region relative to the entire first image and a second ratio of the area of the detected moving object region relative to the entire second image, wherein the first image is captured before the image capturing parameter is set and the second image is captured after the image capturing parameter is set, wherein the determining means (106, 108, S206-S207, S407-S408, S506-S507), in a case where the difference is smaller than a threshold, causes the detecting means (107, S204, S404, S504) to continue using the background model without using a new background model, and wherein the determining means (106, 108, S206-S207, S407-S408, S506-S507), in a case where the difference is equal to or greater than the threshold, causes the detecting means (107, S204, S404, S504) to acquire from the storing means a new background model corresponding to the image capturing parameter set via the input means.