Ultra diffuse galaxies (UDGs) are a new class of galaxies which are recently discovered in high-density regions in the local universe. The surface brightness is as low as a typical dwarf galaxy, however, the half-light radius is as large as the disk of Milky Way. More than one thousand UDGs have already detected, however, the formation process is a still open question. We have studied the effect of periodic supernova feedbacks on the formation of UDGs and the cusp-to-core transformation in CDM halos (Ogiya and Mori 2014; Kato et al. 2019 in prep). N-body simulations have been performed to explore the dynamical response of a stellar system in the dark matter halo against the external potential mimicked the periodic supernova feedbacks. As a result, we successfully reproduced the typical observed features such as the half-light radius and the mass-to-light ratio in UDGs. Our results indicate that periodic supernova feedbacks play an important role in the formation of UDGs.