A room information inferring apparatus that is configured to infer a shape of a room (70, 80, 94, 95, 1201), the room information inferring apparatus comprising: an imaging unit configured to capture an image of a room (70, 80, 94, 95, 1201) that is to be subjected to inferring; a person detection unit configured to detect a person (41a, 41b, 41c, 43, 44, 91) in the image captured by the imaging unit, to acquire a position (42a, 42b, 42c) of the person (41a, 41b, 41c, 43, 44, 91) in the room (70, 80, 94, 95, 1201), and to also detect whether the person (41a, 41b, 41c, 43, 44, 91) 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 (41a, 41b, 41c, 43, 44, 91) 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 (70, 80, 94, 95, 1201) 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 (70, 80, 94, 95, 1201), wherein, when inferring the shape of the room (70, 80, 94, 95, 1201), 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 (41a, 41b, 41c, 43, 44, 91) 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 (41a, 41b, 41c, 43, 44, 91) is moving. an imaging unit configured to capture an image of a room (70, 80, 94, 95, 1201) that is to be subjected to inferring; a person detection unit configured to detect a person (41a, 41b, 41c, 43, 44, 91) in the image captured by the imaging unit, to acquire a position (42a, 42b, 42c) of the person (41a, 41b, 41c, 43, 44, 91) in the room (70, 80, 94, 95, 1201), and to also detect whether the person (41a, 41b, 41c, 43, 44, 91) 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 (41a, 41b, 41c, 43, 44, 91) 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 (70, 80, 94, 95, 1201) 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 (70, 80, 94, 95, 1201), wherein, when inferring the shape of the room (70, 80, 94, 95, 1201), 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 (41a, 41b, 41c, 43, 44, 91) 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 (41a, 41b, 41c, 43, 44, 91) is moving.