A semiconductor integrated circuit on a rectangular semiconductor substrate includes timing generation circuits having the same functions of generating control clock signals to corresponding input buffer circuits based on a control reference clock signal, and a parallel processing circuit unit divided into circuit blocks having equal areas and corresponding to the timing generation circuits. Each circuit block includes clock distribution networks corresponding to the control clock signals. The parallel processing circuit unit carries out processes in parallel for each clock distribution network. Each clock distribution network includes the input buffer circuit; a clock buffer circuit connected to the input buffer circuit and placed approximately in a central position of the corresponding circuit block relative to the semiconductor substrate longitudinal direction; and end devices. The clock buffer circuit outputs a control output clock signal to be distributed and supplied to the end devices.