AbstractWe present a result of IRS spectroscopy of 14 Ultra-Luminous Infrared Galaxies (ULIRGs) in the Extended Groth Strip region. These galaxies are massive and have very high star formation rate. Four objects of this sample are detected in the HST/WFC3 near-infrared imaging. They show very diversified rest-frame optical morphologies, including string-like, extended/diffused, and even spiral with a possible bulge, implying different formation processes for these galaxies. We also search for signatures of active galactic nucleus (AGN) in our sample in the X-ray, mid-infrared and radio bands. This sample is dominated by objects with intensive star formation, only 14–29% of them have AGN activities.