According to one embodiment, a nonvolatile semiconductor memory device includes a semiconductor substrate; an element isolation insulating film buried in the semiconductor substrate so as to isolate adjacent element; a memory cell having a first insulating film and a charge accumulation film; a second insulating film formed on the charge accumulation films of the memory cells and the element isolation insulating film; and a control electrode film formed on the second insulating film. An upper surface of the element isolation insulating film is lower than an upper surface of the charge accumulation film, the second insulating film is provided with a cell upper portion on the charge accumulation film and an inter-cell portion on the element isolation insulating film, and a dielectric constant of the cell upper portion is lower than a dielectric constant of the inter-cell portion.