A semiconductor integrated circuit device includes first to k-th decoders, and a MOS transistor switch group having a hierarchical structure of first to k-th hierarchies and operated on a second voltage level. An n-bit input signal of a first voltage level is divided into k groups (k is an integral number equal to or larger than 2) and input to the first to k-th decoders. The first to k-th decoders decode the input signal, shift the decode results to the second voltage level higher than the first voltage level and output the same. The MOS transistor switch group is supplied with 2n analog inputs at the first hierarchy, selects one of the 2n analog inputs and outputs the selected analog input from the k-th hierarchy.