A skew adjustment circuit, provided in an integrated circuit device having a plurality of signal lines transmitting a plurality of signals respectively, and a plurality of buffer circuits to which a plurality of signals transmitted through the signal lines are respectively input, has: a plurality of delay circuits, respectively provided in stages preceding the buffer circuits; a monitoring circuit monitoring changes in the signals of the plurality of signal lines; and a delay adjustment circuit, which decides delay amounts for the plurality of delay circuits based on a monitoring result output of the monitoring circuit, and sets the delay amounts in the plurality of delay circuits. The monitoring circuit detects, as the monitoring result, a number of signal changes in the signal lines in which a signal change occurs in a monitoring period, and the delay adjustment circuit decides the delay amounts based on the number of signal changes.