A memory error detecting apparatus for detecting an error of a subject memory, the memory error detecting apparatus includes a memory bus connected to the subject memory, a mirror memory connected to the memory bus so as to receive the same data as data to be written into and read from the subject memory, the received data being written into the mirror memory, an address acquiring portion configured to acquire an address related to the data written into the subject memory, a mirror memory controller configured to control data writing or reading to or from the mirror memory on the basis of the acquired address, a comparator configured to compare data read from the subject memory and data read from the mirror memory, and an error detector configured to detect a data error on the basis of a result of the comparison.