A logic circuit design equipment and a logic circuit design method include analyzing input states of all of first cells, respectively, analyzing leakage currents of all of first cells in a case where each first cell is high Vth cell showing a small leakage current at a low speed operation and low Vth cell showing a large leakage current at a high speed operation, respectively, and substituting the first cells for second cells within a range satisfying a timing restriction. Herein, a threshold of the second cell is different from a threshold of the first cell.