Employees'severance and retirement benefits are provided basedon the estimated amounts of projected benefit obligation and the fair value of the plan assets. Prior service costs are recongnized in expenses in equal amounts mainly over 12 years, which is within the average of the estimated remaining service periods of employees, and actuarial gains and losses are recognized in expenses using the straight-line basis mainly over 13 years,which is within the average of the estimted remaining service periods, commencing with the following period.