A flash memory device having a split gate that can prevent an active region and a floating gate electrode from being misaligned, and a method of manufacturing the same, includes sequentially stacking a gate oxide layer and a floating gate conductive layer on a semiconductor substrate, forming an isolation layer in a predetermined region of the semiconductor substrate where the floating gate conductive layer is formed, and defining an active region. Then, a local oxide layer is formed by oxidizing a predetermined part of the floating gate conductive layer on the active region. A floating gate electrode structure is formed by patterning the floating gate conductive layer using the local oxide layer.