We propose to obtain a broad band spectrum of the narrow-line Seyfert 1 (NLS1) NGC 4051. NLS1s are often presumed that they host a relatively small black hole with a very high accretion rate. Such a class would have played an important role in the growth of black holes in a cosmological context. We will measure the intrinsic photon index, amount of reflection, and high energy cutoff for the first time to investigate an accretion disk under a high accretion rate and compare them with conventional broad-line Seyferts.