The present invention relates to a nano-scale flash memory device having a saddle structure, and a fabrication method thereof. Particularly, the invention relates to a highly integrated, high-performance flash memory device having a saddle structure for improving the scaling-down characteristic and performance of the MOS-based flash memory device. According to the invention, a portion of an insulating film around a recessed channel is selectively removed to expose the surface and sides of the recessed channel. A tunneling insulating film is formed on the exposed surface and sides of the recessed channel. On the resulting structure, a floating electrode, an inter-electrode insulating film and a control electrode are formed, thus fabricating the device. Particularly when the floating electrode is made of an insulating nitride film or pluralities of nano-scale dots, an excellent memory device can be made without using an additional mask. According to the invention, the scaling-down characteristic of the device is excellent, and current drive capability can be greatly increased since a channel through which current can flow is formed on the surface and sides of the recessed channel. Also, the ability of the control electrode to control the channel can be enhanced, so that memory write/erase characteristics can be improved.