A detection system is provided for easily detecting information about respective objects seated on a plurality of vehicle seats. An occupant information detection apparatus for a vehicle is disclosed which, in one form, comprises a single photographing section capable of detecting image, a projector lens and a mirror which have viewing angles wider than that of the single photographing section and can independently project the objects seated to the single photographing section to correspond to respective vehicle seats, and a control section for detecting information about objects seated on the respective vehicle seats.