The popular person is the one who is beloved, approaced, chosen by, and attractive to others. These characteristics the person has were developed through the operant and the classical conditioning. For the person (CS) who gives the reinforcer (UCS) simultaneously will get the incentive properties himself, and thus he will be more frequently approached (R) by others and be more popular than those who give no reinforcement. Therefore, it is hypothesized that the. more popular the person is, the more reinforcement he will give to the statement of others in the interpersonal situation. The hypothesis was confirmed in the present study in which the sociometry was used as a measurement of popularity, and the amount of reinforcement was counted from the agreement, nodding or uh-hum, made while listening to the tape of male and female recording as the statement of others.