A leak current calculation apparatus includes an acquiring section for acquiring partial circuit information, and a grouping section for forming a plurality of groups each comprising a part of the partial circuits connected with each other and for generating group information. The apparatus includes a leak difference value calculating section for calculating a leak difference value, which is a difference between a provisional maximum value acquired by adding up the maximum values of the leak current values of all the partial circuits and a sum of maximum values of the leak current values contained in the group information of the groups, and a maximum leak current calculating section for calculating the maximum leak current value of the integrated circuit by adjusting the provisional maximum value with the leak difference value.