A semiconductor memory device includes a page buffer circuit and an arrangement of memory elements each including: a gate electrode provided on a semiconductor layer with an intervening gate insulating film; a channel region provided beneath the gate electrode; a diffusion area provided on both sides of the channel region, having an opposite polarity to the channel region; and a memory functioning member provided on both sides of the gate electrodes, having a function of storing electric charge. The page buffer circuit provides a common resource shared between a memory array controller and a user. The page buffer circuit has two planes containing random access memory arrays. The page buffer circuit also includes a mode control section to facilitate access to the planes over a main bus in user mode and access to the planes by the memory array controller in memory control mode.