Semiconductor memory devices and methods for manufacturing the same are provided. The device may include vertical channel structures that are two-dimensionally arranged on a substrate and vertically extend from the substrate. The device may also include bit lines on the vertical channel structures, and each of the bit lines may be commonly connected to the vertical channel structures arranged in a first direction. The device may further include common source lines that extend between the vertical channel structures in a second direction intersecting the first direction and a source strapping line that is disposed at the same vertical level as the bit lines and electrically connects the common source lines to each other.