The intergrain magnetoresistance (IMR) of La_0.7 Sr_0.3 MnO₃ (LSMO) thin films at 77 K was examined. All LSMO films were grown on step-edged (100) GaAs substrates (step-edge angles ranged from 0 to 80°) by the Ar–F excimer laser ablation (pulsed laser deposition) method. Grains were formed by nanocolumns standing normal to the GaAs surface, resulting in the formation of mechanically contacting grain boundaries. Unlike the conventional bicrystal grain boundary, the present nanocolumn boundaries offered tunneling resistance with negligible influence of the boundary angles. The IMRs showed marked reduction with the application of magnetic field below 100 mT, followed by a gradual change with increasing field. They also clearly showed nanocolumn boundary angle dependence even in the large-angle region.