We report the achievement of Bose-Einstein condensation of ytterbium (Yb) atoms by an all-optical method. A ytterbium atomic beam from an oven is first decelerated by a Zeeman slower using the singlet transition, and then captured by a magneto-optical trap using the intercombination transition. Evaporative cooling is performed in a novel crossed optical trap, which results in the formation of condensates of about 5x10(3) atoms of 174 Yb. We determine the scattering length of 174 Yb to be between I and 3 nm by combining the behavior of the condensate and the result of photoassociation measurements. The prospects of Yb condensates are also discussed.