We investigate how the spin memory loss at interfaces affects the spin transfer torque in the framework of the drift-diffusion model. The spin memory loss changes the spin accumulation in the non-magnetic spacer separating the two ferromagnets in a spin valve structure and, thus, the spin transfer torque. By comparing theoretical values of the spin transfer torque with experimental results, we found that non-zero spin memory loss is essential to explain the experimental switching current densities in the current-induced magnetization switching. The spin memory loss determined by the comparison is in good agreement with the value determined by experimental measurement of giant magnetoresistance.