Some politicians are proposing more corporate tax burden in order to reduce budget deficits and finance the increasing social welfare expenditures. It is also argued that a few extremely well performing firms should be taxed more heavily since they are charged only the average effective corporate tax rates similar to or slightly lower than those of small and medium size firms. The discussion of horizontal and vertical tax burdens should be based on objective and reliable current distribution of tax burdens. This study presents the distribution of corporate tax burdens by focusing on the average effective tax rates based on various firm characteristics such as the corporate type, the firm size, industry, location, and so on, using data from Statistical Yearbook of National Tax and financial statements of individual firms that are open to the public. In order to study the validity of effective tax rates measured from financial statements, we analyze the size of errors by comparing to those measured from Statistical Yearbook of National Tax. We also study what determinesthe effective tax rates using firm level data and how responsive investment and employment are responsive to the changes in effective tax rates using industry level data.