A semiconductor device constituting a decoder circuit for memory selection and having a smaller area is provided by using surrounding gate transistors (SGTs), which are vertical transistors. In a decoder circuit formed by a plurality of MOS transistors arranged in m rows and n columns, the MOS transistors that constitute the decoder circuit are arranged on a planar silicon layer formed on a substrate. Each has a structure including a drain, a gate, and a source arranged in a vertical direction, the gate surrounding a silicon pillar. The planar silicon layer is formed by a first active region of a first conductivity type and a second active region of a second conductivity type, and the regions are connected to each other via a silicide layer formed on the surface of the planar silicon layer. Consequently, a semiconductor device that constitutes a decoder circuit having a smaller area is provided.