A semiconductor memory system includes a memory device including a plurality of memory blocks; a partial memory block detector suitable for detecting at least one partial memory block among the plurality of memory blocks; an open page detector suitable for detecting addresses and a number of a plurality of open pages among a plurality of pages included in the partial memory block; and a controller suitable for controlling the memory device to perform a one-shot program operation with dummy data according to the addresses and the number of the plurality of open pages.