We refined and expanded the previous research. In the previous research, fixed costs are increased when companies have large uncertainties. For example Banker et al.（ 2014）, using the magnitude of the variance of sales as a surrogate variable of uncertainty, they verified the variance of sales and increased fixed cost per fiscal year. We verified quarterly data. We focused on breakdown of sales variance and broke down into predictable variance and unpredictable variance. We hypothesized that they have different effects on fixed costs. Then, the components were decomposed using the state-space model. As results,（ 1） Cost of goods sold is that seasonal fluctuations do not affect fixed costs, （2） Selling, general and administrative costs seasonal fluctuation is that fixed costs increase,（ 3） Unforeseeable fluctuations are to increase fixed costs of both cost of goods sold and selling, general and administrative costs, were revealed.