LaMn_1-xCu_xO₃ (x=0.05 to 0.15) samples were prepared and their crystal structure and magnetic properties were studied by recording neutron powder diffraction patterns and M-H loops at different temperatures. Even though the samples were free from impurity, the x=0.05 and 0.10 samples are found to crystallize in mixture of R^-₃c  and Pnma space group with dominate fraction of former one. The phase fraction for x=0.10 sample is found to vary with temperature especially below the ferromagnetic T_c. The x=0.15 sample could be refined based on Pnma space group. The patterns at low temperatures could be refined by considering magnetic reflections corresponding to ferromagnetic structure. The magnetic moments of Mn ion are found to be along b axis with typical value of 3.40 (3) µ_B  for x=0.10 sample. From the analysis of the diffraction patterns and the magnetization data, it is found that x=0.15 sample exhibit spin canting.