Semiconductor memory

A semiconductor memory includes a stack section comprising a first area including a plurality of first conductors and a plurality of first insulators alternately stacked in a first direction and memory cells, and a second area including respective end portions of the plurality of stacked first conductors and the plurality of stacked first insulators, a plurality of contact plugs respectively reaching the plurality of first conductors in the second area, first and second supporting portions configured respectively to pass through the stack section in the first direction and arranged in a second direction, which crosses the first direction, in the second area, and a layer between respective adjacent first insulators, among the plurality of first insulators that are stacked, between the first supporting portion and the second supporting portion, wherein the layer is made of a material that is different from that of the first conductors.