Abstract. Simplified explosion models of super-Chandrasekhar-mass C-O white dwarfs (WDs) are constructed with parameters such as WD mass and 56 Ni mass. Their light curves are obtained by solving one-dimensional equations of radiation hydrodynamics, and compared with the observations of SN 2009dc, one of the overluminous Type Ia supernovae, to estimate its properties. As a result, the progenitor of SN 2009dc is suggested to be a 2.2-2.4-M C-O WD with 1.2-1.4 M of 56 Ni, if the extinction by its host galaxy is negligible. To study the properties of SN 2009dc from its light curves (LCs), simplified explosion models of super-Ch-mass C-O WDs are constructed in a manner similar to Maeda & Iwamoto (2009 . Then the density and velocity structures are obtained by scaling those of W7 (Nomoto et al. 1984, Thielemann et al. 1986) with M W D and E kin . For its abundance distribution, the model consists of ECEs, 56 Ni, IMEs, and C-O layers, from the center to the surface. However, mixing is assumed for a certain region due to the observed slow Si ii line velocity (Yamanaka et al. 2009). The parameter ranges in this study areM IM E is hereafter not indicated. Any model whose E kin is not positive is excluded.The STELLA code is used to calculate the LCs, which solves one-dimensional equations of radiation hydrodynamics (e.g., Blinnikov et al. 1998). In this study, multi-band (U -, B-, V -, R-, and I-band) LCs are obtained, as well as bolometric ones. The "bolometric" LCs in the observations are not truly bolometric, but cover uvoir. For SN 2009dc, the observed uvoir luminosity is assumed to be ∼1.6 the integrated BVRI one (Yamanaka et al. 2009), which is common for normal SNe Ia (Wang et al. 2009). Since it is still unknown whether this assumption is true for overluminous SNe Ia, BVRI LCs are compared in the following.The resultant BVRI LCs of the models show a similar tendency to that in Maeda & Iwamoto (2009); a massive WD model has a wider BVRI LC and vice versa. Since SN 314 at https://www.cambridge.org/core/terms. https://doi