Semiconductor memory device comprising memory cell array having dynamic memory cells using floating body transistor and method of operating the same

A semiconductor memory device and an operation method thereof are provided to reduce the refresh time by refreshing memory cells connected to all word lines at the same time. A semiconductor memory device comprises a memory cell array(50) and a controller. The memory cell array comprises a plurality of memory cells(MC1~MCi). A plurality of memory cells are connected to a plurality of word lines(WL1~WLi), a plurality of bit lines(BL1~BLj) and a plurality of source lines(SL1~SLi). Each memory cell has a floating body transistor. The controller supplies the read control signal to at least one word line and at least one source line in reading. The controller applies the refresh control signal to at least one word line in the refresh operation.