A person position detection apparatus which outputs a position of an person as a distance image, comprising: a distance image generation unit which generates a two-dimensional distance image by measuring a distance to a subject including the person on the basis of a light transmission time, wherein a signal of the distance image indicates the distance from the distance image generation unit to the subject; an person image generation unit which generates an person image in which the person is extracted from the distance image of the subject; an installation angle detection unit which detects an installation angle of the distance image generation unit, and a person distance/posture detection unit which detects a distance to the person or a posture of the person, wherein the person image generation unit includes a differentiator performing a process of removing a background other than the person from the distance image of the subject using a threshold value, wherein the background removing process performed by the differentiator is a process of allowing a passage of the signal of the distance image in a region in which a distance difference with the background is larger than the threshold value and of replacing the signal with no signal in a region in which the distance difference with the background is equal to or smaller than the threshold value, and characterized in that said threshold value for removing the background in the differentiator is set in response to the installation angle of the distance image generation unit detected by the installation angle detection unit and the detection result of the person distance/posture detection unit. a distance image generation unit which generates a two-dimensional distance image by measuring a distance to a subject including the person on the basis of a light transmission time, wherein a signal of the distance image indicates the distance from the distance image generation unit to the subject; an person image generation unit which generates an person image in which the person is extracted from the distance image of the subject; an installation angle detection unit which detects an installation angle of the distance image generation unit, and a person distance/posture detection unit which detects a distance to the person or a posture of the person, wherein the person image generation unit includes a differentiator performing a process of removing a background other than the person from the distance image of the subject using a threshold value, wherein the background removing process performed by the differentiator is a process of allowing a passage of the signal of the distance image in a region in which a distance difference with the background is larger than the threshold value and of replacing the signal with no signal in a region in which the distance difference with the background is equal to or smaller than the threshold value, and characterized in that said threshold value for removing the background in the differentiator is set in response to the installation angle of the distance image generation unit detected by the installation angle detection unit and the detection result of the person distance/posture detection unit.