Provided are a semiconductor device and a method of forming the same. According to the method, a first buried oxide layer is locally formed in a semiconductor substrate and a core semiconductor pattern of a line form, a pair of anchor-semiconductor patterns and a support-semiconductor pattern are formed by patterning a semiconductor layer on the first buried oxide layer to expose the first buried oxide layer. The pair of anchor-semiconductor patterns contact both ends of the core semiconductor pattern, respectively, and the support-semiconductor pattern contacts one sidewall of the core semiconductor pattern, the first buried oxide layer below the core semiconductor pattern is removed. At this time, a portion of the first buried oxide layer below each of the anchor-semiconductor patterns and a portion of the first buried oxide layer below the support-semiconductor pattern remain. A second buried oxide layer is formed to fill a region where the first buried oxide layer below the core semiconductor pattern.