A nonvolatile semiconductor memory transistor includes an island-shaped semiconductor having a source region, a channel region, and a drain region formed in this order from the Si substrate side, a floating gate surrounding the outer periphery of the channel region with a tunnel insulating film interposed therebetween, a control gate surrounding the outer periphery of the floating gate with an inter-polysilicon insulating film interposed therebetween, and a control gate line connected to the control gate and extending in a predetermined direction. The floating gate extends to regions below and above the control gate and to a region below the control gate line. The inter-polysilicon insulating film is interposed between the floating gate and the upper surface, lower surface, and inner side surface of the control gate and between the control gate line and a portion of the floating gate that extends to the region below the control gate line.