A spatial disturbance that occurs when an access is concentrated in a specific memory area in a volatile semiconductor memory like DRAM is properly solved by a memory controller. The memory controller includes a concentration access detection part generating a concentration access detection signal when an address for accessing a specific memory area among memory areas of volatile semiconductor memory is concentratedly received. In the case that the concentration access detection signal is generated, the memory controller includes a controller for easing or preventing corruption of data which memory cells of the specific memory area and/or memory cells of memory areas adjacent to the specific memory area hold.