Memory blocks provided to share a sense amplifier band, a global IO (GIOB) bus provided in common to the memory blocks for transferring internal data, and local IO bus lines provided corresponding to the memory blocks are connection-controlled based on signals related to a column select operation. Driving memory blocks independently from each other permits each memory block to be used as a bank, and if one memory block is accessed during activation of another memory block, data can be prevented from colliding on the global IO bus. A main memory with high page hit rate is implemented using a semiconductor memory device with a shared-sense amplifier configuration. When a memory block sharing a sense amplifier coupled to another memory block is addressed, the another memory block is inactivated and then addressed memory block is accessed, when a valid data is output, such valid data outputting is signaled by a data valid signal.