Provided are a semiconductor memory device with guard pillars and a manufacturing method thereof. The semiconductor memory device includes a substrate having a memory region and a periphery region surrounding the memory region, a plurality of bit line structures, a plurality of contacts, a plurality of guard pillars and a plurality of capacitors. The bit line structures are arranged parallel to each other on the substrate in the memory region. The contacts are disposed between the adjacent bit line structures and electrically connected to the substrate. The guard pillars are disposed on the substrate and located between the adjacent bit line structures at the boundary between the memory region and the periphery region. The capacitors are disposed on the plurality of contacts to be electrically connected to the plurality of contacts.