We present an optical spectropolarimetric observation of the unique Type Ib supernova ( SN ) 2005bf at 8 days after the second maximum .
The data , combined with the polarization spectrum taken at 6 days before the second maximum ( Maund et al .
2007a ) , enable us to closely examine the intrinsic properties of the SN .
The polarization percentage is smaller at the later epoch over a wide wavelength range , while the position angle is similar at the two epochs .
We find that an assumption of complete depolarization of strong lines at the emission peak is not necessarily correct .
The intrinsic polarization of the SN is larger , and thus , the ejecta of SN 2005bf would be more asymmetric than previously expected .
The axis ratio of the photosphere projected on the sky deviates from unity by at least 20 % .
If the position angle of interstellar polarization is aligned with the spiral arm of the host galaxy , the deviation is larger than 25 % .
The line polarization at the He i , Ca ii and Fe ii lines is also smaller at the later epoch .
The changes in the position angle across these lines , which were observed at the earlier epoch , are still marginally present at the later epoch .
The similar polarimetric behavior suggests that the distributions of these ions are correlated .
Properties of polarization , as well as the light curve and the spectra both at photospheric and nebular phases , can be explained by an aspherical , possibly unipolar explosion of a WN star in which the blob of ^ { 56 } Ni penetrates C+O core and stops within the He layer .