The temporal variation of (14)C concentrations in atmospheric CO(2) samples collected every 10 days was measured in the Takao area of Kanazawa, Ishikawa prefecture, Japan (36.52 degrees N, 136.64 degrees E), from April 1991 to December 1995. The monthly mean levels of (14)C concentration in the Takao area demonstrated 10-50 parts per thousand lower concentrations than the background levels only in the winter season. This decrease seemed to be caused by the local fossil fuel contribution by heating in the winter season in the Takao area, which is located in an urban region near the center of Kanazawa. It is noteworthy that a remarkable peak was observed from late April to mid-May each year from 1991 to 1995 in the variation of (14)C concentrations in atmospheric CO(2). This phenomenon is similar to that of the so-called "spring peak" observed in Japan for other radionuclides.