To provide an image monitoring apparatus for imaging a monitoring space and detecting that there is a suspicious person hiding his/her face which can discriminate between a full face helmet and the back of a person's head.

An image monitoring apparatus 3 for detecting a suspicious person hiding his/her face with a helmet or the like in a monitoring space includes: an imaging section 31 for periodically imaging the monitoring space to acquire monitoring images; a storage section 33 for storing face feature information beforehand; a head extraction section 342 for extracting an input head area corresponding to a person's head from the monitoring images; a face feature determination section 343 for determining whether the input head area has feature information on a face according to the face feature information; a high luminance area extraction section 344 for determining whether there is a high luminance area that is equal to or more than a predetermined area in the input head area; and a suspicious person detection section 345 for determining that there is a suspicious person hiding his/her face if the face feature determination section determines that there is no feature information on a face and the high luminance area extraction section determines that there is a high luminance area.