A plurality of blocks are optimally placed within a short process time while minimizing the exceeding of the delay time. Input means receives information on a logic circuit having a hierarchical structure including a plurality of blocks, and RTL estimation means calculates a delay time in the blocks in advance. Path detection means detects a timing path extending via a plurality of blocks, and delay calculation means calculates a delay value while assuming that the inter-block interconnect length is zero. Delay margin setting means sets a delay margin obtained by subtracting the delay value from a predetermined delay time. The delay margin forms a part of an objective function as a weight on the virtual interconnect length between each of the inter-block terminal pairs in the placement process, and the blocks are automatically placed by using the objective function.