Black hole thermodynamics is one of the most important topics of theoritical physics in resent decades. Theoretically black hole thermodynamics provides a background for studying gravitational theory and quantum gravity. Hawking showed that the black holes obey a set of four thermodynamical laws similar to ordinary thermodynamics. In this thesis, reviewing the basics of general relativity, we try to get a better understanding of the meaning of the frst law of black hole thermodynamics. For this reason we use the Wald approach, implying the black hole entropy as a Noether charge due to di?eomorphism symmetry. In this approach, considering the isometries and symmetries of the system in the framework of covariant phase space, we ascribe a Noether current and a Noether charge to lacal symmetry of di?eomorphism, associated to a defnit killing vector. Then considering a timelike killing vector we show that the Noether charge due to the corresponding di?eomorphism can be interpreted as the entropy of the black hole. We can see that this quantity is the same as Bekenstain-Hawking formula for the Hilbert-Einstein theory. This result is achieved by considering asymptotic ?at metric boundary conditions, as well as a stationary black hole with a bifurcation killing horizon. We also practiced this method for dilaton gravity to fnd the corresponding black hole entropy