Abstract: The present invention provides a semiconductor IC and a method for designing the same which adjusts the clock skews on a chip without additional delay circuit. A decrease in design time is realized when the semiconductor IC includes hard megacells (whose functions have been confirmed) or standard cell blocks. In the case of a semiconductor IC including hard megacells and a standard cell blocks, each megacell and standard cell block according to the present invention has sub-clock buffers on every row, for example, sub-clock buffers on the row and sub-clock buffers on the row in the megacell. The adjustment needed for accommodating clock skews on a chip is determined by calculating a delay time for the various IC chip blocks. Next, sub-clock buffers are chosen based on a result of a calculation for the delay time. Finally, the wiring design is completed which minimizes clock skew.