A person state detection apparatus (10) according to the present disclosure includes an acquisition unit (11) for acquiring a two-dimensional image obtained by capturing a person, a skeletal structure detection unit (12) for detecting a two-dimensional skeletal structure of the person based on the acquired two-dimensional image, an estimation unit (13) for estimating a height of the person standing upright in a two-dimensional image space based on the detected two-dimensional skeletal structure, and a state detection unit (14) for detecting the state of the person based on a height of an area where the person is present in the two-dimensional image.