A memory diagnosis apparatus to diagnose whether a fault occurs in a memory includes a diagnosis execution unit to divide the memory into a plurality of areas, select two or more base areas that are diagnostic targets from among the areas to carry out a memory diagnosis including a reading test and a writing test, and perform only the writing test in carrying out the memory diagnosis on a same base area for second or more times. The diagnosis execution unit is implemented by an arithmetic device that is a processing circuit that executes a memory diagnosis program stored in a storage device.