Abstract: An information recording and reproducing apparatus having a self-diagnosis information storage mechanism is provided. This apparatus stores self-diagnosis information without increasing the storage capacity thereof and erasing important error information. According to the present invention, any inconforming of the apparatus itself or the quality of a signal recorded in the recording medium and error information regarding thereon is stored in a memory through discrimination/control device so that the information is read out from outside and at the same time, when a vital error occurs, storage of error information thereafter is inhibited while, as regards, information not stored, only the logic sum thereof is stored.