An object detection device is provided with a binary difference image generation unit that generates a binary difference image (C) wherein the difference value between a background image (B) and an image for detection (F) is binarized with a specified threshold value therefor. Said background image (B): represents the temperature distribution of a detection area; and is the reference image for the nonexistence of an object for detection within the detection area. Said image for detection (F): represents the temperature distribution of the detection area; and is the image to be detected, being for the purpose of detecting the object for detection in the detection area. Said object detection device is also provided with: a binary second derivative image generation unit that generates a binary second derivative image (D) wherein the second derivative value of the image for detection (F), or of a smoothed image (F') generated by smoothing the image for detection (F), is binarized with a specified threshold value for the derivative value; and an object detection unit that on the basis of the logical product of the binary difference image (C) and the binary second derivative image (D), detects the object to be detected.