An image forming apparatus is capable of specifying the type of an occurring abnormality to a certain extent while avoiding the increasingly complicated control that is caused when a plurality of abnormalities is detected individually according to the presence of their respective causes. A normal group data set, which is a collection of normal value combinations relating to grouped information constituted by a plurality of information of differing types, is stored in RAM or ROM serving as information storage means of a control unit. At least two or more sets of grouped information, comprising first grouped information constituted by a plurality of different types of information, and second grouped information constituted by a plurality of information in a different combination to that of the first grouped information, are obtained from the RAM, the ROM, various sensors, and an operation display unit. A CPU serving as determining means determines a Mahalanobis distance for each set of grouped information on the basis of the normal group data set and the obtained results of each set of grouped information, and uses this Mahalanobis distance to determine the presence of an abnormality according to categories.