Kojima, Naoki2018-07-092018-07-092017-02Theoretical Economics Letters, 2017, 7, 187-1922162-2086https://doi.org/10.4236/tel.2017.72016http://hdl.handle.net/123456789/1736The present paper investigates the multi-dimensional mechanism design in which buyers have taste and budget as their private information. The paper shows an easy proof of a two-dimensional optimal direct mechanism by a one-dimensional indirect mechanism: A canonical mechanism in the traditional one-dimensional setting, i.e., function of one variable, the buyer’s taste. It also sheds light on where the difficulty lies implementability of a general direct mechanism—not optimal—by a canonical mechanism.enMulti-Dimensional MechanismIndirect MechanismBudget ConstraintRevelation PrincipleArticle