A stack-type nonvolatile semiconductor device comprises a memory device formed on a substrate including a semiconductor body elongated in one direction, having a cross section perpendicular to a main surface, having a predetermined curvature, a channel region on the semiconductor body along the circumference, a tunneling insulating layer on the channel region, a floating gate on the tunneling insulating layer, insulated from the channel region, a high dielectric constant material layer on the floating gate, a metallic control gate on the high dielectric constant material layer, insulated from the floating gate, and source and drain regions adjacent to the metallic control gate on the semiconductor body, an inter-insulating layer on the memory device, and a conductive layer on the inter-insulating layer, and a memory device formed on the conductive layer including, a semiconductor body elongated in one direction having a cross section perpendicular to a main surface, having a predetermined curvature, a channel region along the circumference of the semiconductor body, a tunneling insulating layer on the channel region, a floating gate on the tunneling insulating layer, electrically insulated from the channel region, a high dielectric constant material layer on the floating gate, a metallic control gate on the high dielectric constant material layer, insulated from the floating gate, and source and drain regions adjacent to the metallic control gate.