We investigate the dependence of occurrence of bars in galaxies on galaxy properties and environment . We use a volume-limited sample of 33,391 galaxies brighter than M _ { r } = -19.5 + 5 log h at 0.02 \leq z \leq 0.05489 , drawn from the SDSS DR 7 . We classify the galaxies into early and late types , and identify bars by visual inspection . Among 10,674 late-type galaxies with axis ratio b / a > 0.60 , we find 3,240 barred galaxies ( f _ { bar } = 30.4 \% ) which divide into 2,542 strong bars ( f _ { SB 1 } = 23.8 \% ) and 698 weak bars ( f _ { SB 2 } = 6.5 \% ) . We find that f _ { SB 1 } increases as u - r color becomes redder , and that it has a maximum value at intermediate velocity dispersion ( \sigma \simeq 150 km s ^ { -1 } ) . This trend suggests that strong bars are dominantly hosted by intermediate-mass systems . Weak bars prefer bluer galaxies with lower mass and lower concentration . In the case of strong bars , their dependence on the concentration index appears only for massive galaxies with \sigma > 150 km s ^ { -1 } . We also find that f _ { bar } does not directly depend on the large-scale background density when other physical parameters ( u - r color or \sigma ) are fixed . We discover that f _ { SB 1 } decreases as the separation to the nearest neighbor galaxy becomes smaller than 0.1 times the virial radius of the neighbor regardless of neighbor ’ s morphology . These results imply that strong bars are likely to be destroyed during strong tidal interactions , and that the mechanism for this phenomenon is gravitational and not hydrodynamical . The fraction of weak bars has no correlation with environmental parameters . We do not find any direct evidence for environmental stimulation of bar formation .