A fibrous cap develops on the luminal side of the lipid core in an atherosclerotic plaque. A rupture of the fibrous cap may cause cardiac and cerebral infarctions. In the previous studies, we obtained human carotid arteries and thoracic aortas at autopsy and conducted uniaxial stretching tests for strip-like specimens. Then we obtained the stress-strain relationships for fibrous caps in white and yellow plaques and for normal regions on the intimal side of the arterial wall. Carrying out curve fitting with user-defined functions in the software Igor Pro (WaveMetrics, Inc.), we determined two or four material constants in Ogden model, which is an incompressible and isotropic hyperelastic model, for fibrous caps and normal regions. The results showed good agreements with experimental results. For fibrous caps, the material constants in Ogden model take larger values in a white plaque than in a yellow plaque for both carotid artery and thoracic aorta.