The properties of the unique Type Ib supernova (SN) 2005bf are studied through the theoretical modeling of the early phase spectra and the light curve. The high velocity FeII lines in the earliest spectra are not the consequence of a jet-like explosion, but are naturally explained by a lower ionization state of Fe in the outermost layer due to the existence of the hydrogen. The velocities of the He lines measured from the position of the absorption minimum increase with time. Such a behavior is unprecedented, and can be understood if 56Ni is not fully mixed with the He layer. An increasing deposition of γ-rays in the He layer is necessary to produce more and more non-thermal electrons. Therefore it is also suggested that the C+O layer between 56Ni and the He layer is not very thick. The progenitors of Type Ib supernovae (SNe) and Type Ic SNe are briefly discussed by comparing SN 2005bf with other Type Ib/c SNe. We suggest that the mixig of 56Ni plays an important role to make the difference between Type Ib SNe and Type Ic SNe.