PURPOSE: To highly precisely adjust a clock in a few hardware.

CONSTITUTION: One of reference clocks distributed from the output of a clock distributing LSI 1 by using a tree-shaped wiring 2 is received by one LSI terminal, and a difference between the output phase of the reference clock and the output phase of a clock generated from a clock source which is the same as the reference clock, and allowed to pass through a general distribution path is observed. Thus, the phase adjustment of the clock can be attained.