A room information inferring apparatus that is configured to infer a shape of a room , the room information inferring apparatus comprising: an imaging unit configured to capture an image of a room that is to be subjected to inferring; a person detection unit configured to detect a person in the image captured by the imaging unit , to acquire a position of the person in the room , and to also detect whether the person at a detected position is moving or stationary by performing processing for tracking a detected person; a presence map generation unit configured to generate a presence map indicating a distribution of detection points corresponding to persons detected in a plurality of images captured at different times, the presence map indicating a detection point of said distribution of detection points to be a stationary point if the person detection unit detects a person corresponding to said detection point to be stationary, and indicating a detection point of said distribution of detection points to be a moving point if the person detection unit detects a person corresponding to said detection point to be moving, and an inferring unit configured to infer a shape of the room based on the presence map , wherein the inferring unit is adapted to infer that a polygon circumscribed around the distribution of detection points in the presence map is the shape of the room , wherein, when inferring the shape of the room , the inferring unit is adapted to deem that a wall surface is outward by a predetermined distance from a shape obtained as said polygon circumscribed around the distribution of detection points in the presence map , wherein in a case of a detection point at which the person is stationary, the inferring unit is adapted to set the predetermined distance lower than in a case of a detection point at which the person is moving. an imaging unit configured to capture an image of a room that is to be subjected to inferring; a person detection unit configured to detect a person in the image captured by the imaging unit , to acquire a position of the person in the room , and to also detect whether the person at a detected position is moving or stationary by performing processing for tracking a detected person; a presence map generation unit configured to generate a presence map indicating a distribution of detection points corresponding to persons detected in a plurality of images captured at different times, the presence map indicating a detection point of said distribution of detection points to be a stationary point if the person detection unit detects a person corresponding to said detection point to be stationary, and indicating a detection point of said distribution of detection points to be a moving point if the person detection unit detects a person corresponding to said detection point to be moving, and an inferring unit configured to infer a shape of the room based on the presence map , wherein the inferring unit is adapted to infer that a polygon circumscribed around the distribution of detection points in the presence map is the shape of the room , wherein, when inferring the shape of the room , the inferring unit is adapted to deem that a wall surface is outward by a predetermined distance from a shape obtained as said polygon circumscribed around the distribution of detection points in the presence map , wherein in a case of a detection point at which the person is stationary, the inferring unit is adapted to set the predetermined distance lower than in a case of a detection point at which the person is moving. <EOS>