The purpose of the present experiments was to examine the relations between personality traits and sensory-motor learning abilities in adults, under the two conditions of neutral (Exp. 1) and stressful instructions (Exp. 2). Twenty one college boys and girls served as Ss in Exp. 1, and 18 students in Exp. 2, and the apparatus used was a stylus maze with a buzzer which would sound each time Ss made an error. Measurements taken were a) number of repetitions req-u ired to reach the criterion of learning (R), b) total number of errors made in reaching the criterion (E), and c) total time spent (T). Under the neutral instruction, Ss were required to learn three tasks with free speed, and after 24 hours they were again required to learn them. A month later, they were instructed to learn the same mazes with the instruction that would make them stressful. In Exp. 2, they were told to learn as correctly and quickly as possible, and were informed time spent every five seconds. The summary of the present experiments was as follows. 1. In Exp. 1, Ss who obtained a high score in Rhathymia tended to take a small Learning Index (LI=_??_), while in Exp. 2, Ss who were lacking in objectivity and had inferiority feelingshad a tendency to take a small LI. It might be stated that Ss with such characteristics would be apt to be much motivated by the psychological stress.