We report several recent findings on income distribution. Using high-frequency data for personal income-tax in Japan, we have found that the probability distribution function of the growth-rate is independent from the income. We show that this Universality combined with the time-reversal invariance of the income distribution leads to the Pareto's law. We also find the same Universality holds for company's taxable income in Japan. (C) 2002 Elsevier Science B.V. All rights reserved.