A non-volatile semiconductor storage device has a plurality of memory strings with a plurality of electrically rewritable memory cells connected in series. Each of the memory strings includes: a first columnar semiconductor layer extending in a direction perpendicular to a substrate; a charge accumulation layer formed on the first columnar semiconductor layer via a first air gap and accumulating charges; a block insulation layer contacting the charge accumulation layer; and a plurality of first conductive layers contacting the block insulation layer.