Fudan Univ, Dept Phys, Shanghai 200433, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
; Natl Taiwan Univ, Dept Phys, Taipei 106, Taiwan
We compute the cosmological perturbations generated in the brane world inflation driven by the bulk inflaton. Different from the model in which inflation is a brane effect, we exhibit the modification of the power spectrum of scalar perturbations due to the existence of a fifth dimension. With the change of the initial vacuum, we investigate the dependence of the correction of the power spectrum on the choice of the vacuum.