Doping effect of nonmagnetic impurities, p-CyDOV-H (reduced form of p-CyDOV), on the organic spin-Peierls (SP) system, 3-(4-cyanoplienyl)-1,5-dimethyl-6-oxoverdazyl (p-CyDOV) radical crystal, has been studied by measuring the temperature dependence of the magnetic susceptibility (T = 2.0-300 K) and the field dependence of the magnetization (H = 0-55 T) of the diluted p-CyDOV radical crystals, (p-CyDOV)(1-x)(p-CyDOV-H)(x) (x = 0, 0.01, 0.03, 0.05, 0.07, and 0.10). The effect of doping on SP system is very remarkable. The SP transition temperature (T-SP = 15.0 K) decreases rapidly upon p-CyDOV-H doping and the SP state almost disappears in the lightly doped sample with x = 0.05. The susceptibility and magnetization of diluted radical crystal with x = 0.01 and 0.03 below T-SP can be explained by the sum of the susceptibilities and magnetizations of the spin-Peierls state, antiferromagnet, and Curie impurity, respectively, indicating the coexistence of SP and antiferromagnetic phases in the doped SP system at low temperature. This work is the first report of the high-field magnetization study of the doping effect of nonmagnetic impurities on the organic SP transition system.