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 device of a control unit. At least two or more sets of grouped information, including 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.