Title: Quantum curves and Brane transitions Abstract: The ABJM theory is the worldvolume theory of N multiple M2-branes. In IIB string theory, the ABJM theory is described by the brane configuration of an NS5-brane, a (1,k)5-brane and N multiple D3-branes between their 5-branes. By the localization technique, this theory reduces to the matrix model (called ABJM matrix model) and the grand partition function of this matrix model is written by the quantum curve associated to the local F_0. There are generalizations written by the quantum curves associated to the del Pezzo curves whose parameters are transformed by the exceptional Weyl groups. We discuss the brane transitions from the viewpoint of the curves. When we identify the Weyl group as the brane transitions, we not only reproduce the Hanany-Witten transitions under the identification, but also find new transitions and propose the local rule of brane transition for them.