When we perform a learning experiment using the avoidance training by putting mouse, as an experimental animal in a jump-box, standard deviation becomes larger than we expect among individuals of the same strain, even though we use the inbred strain. We select male and female of ddN strain mouse. When these mice jump-up within 3 seconds after a conditioned stimulus in more than 20 times out of the first 60 trials, we let them mate. Through 7 generations by brother and sister matings we have improved genetic selection; male and female mice show the reaction in more than 15 times of the first 30 trials. Then, we let them mate. Comparing with the ealier generation of inbred mouse, the standard deviation in the 10th generation (ddN-F10) becomes smaller. And no remarkable differences in male and female on the avoidance ability are noticed. We also study on comparing the formation of learning by avoidance training and the short- and long-term memories of the reactions after training between the ddN-F10 strain and following inbred strains, i.e., C3H, DBA, C57-BL, RF, AKR, C58, D103, C6, and CBA. AKA, ddN-F10, DBA, C58, and C3H learned fastest, whereas RF, D103, C6, and CBA strains learned slowest. As to the long-term memory, ddN-F10, DBA, C58, C57-BL, and C3H perform superior to RF and D103. Except for the ddN-F10, other strains show a large standard deviation. In conclusion, we can establish laboratory mice using the avoidance learning for genetic improvement.