Musicians and nonmusicians were tested in the recognitions of four kinds of dichotically presented music stimuli : recorded tones, chords, rhythms and melodies. Nonmusicians were 18 subjects (A), who worked in fireman's agency in Paris, France, whose ages ranged from 18 to 28 years (average : 20.2 years) and whose years of musical experiences ranged from 0 to 5. Musicians were 8 students in musical college (Conservatoire national supérieur de Musique de Paris): 5 right-handed (B) and 3 left-handed persons (C), whose ages ranged from 18 to 25 years (average : 21.8 years), whose years of musical experiences ranged from 10 to 18 (average: 12.8 years).     1) In the tone test, the mean score for right and left ears were nearly the same for both A and B.     2) The chord test revealed a significant left ear superiority for A, and the tendency of the higher score in left ear was seen for B.     3) In the rhythm test, the score for the right ear had a tendency to be higher than the one for the left ear, both in A and B.     4) In the melody test, the score showed a tendency of left ear superiority for A, but the tendency of right ear superiority was seen for B.     Bever and Chiarello (1974) found a right ear reference in the detection of musical stimuli when they used musicians as subjects. Johnson made the dichotic listening task involving violin for musicians and nonmusicians. The musicians demonstrated a right ear superiority, while the nonmusicians performed better with the left ear. He interpreted that musicians mainly used the left hemisphere to process musical stimuli, while nonmusicians used the right hemisphere.     The results of Bever and Chiarello, and Johnson nearly agree with the results of our musical dichotic listening test for nonmusicians and musicians in France as well as the results of our former studies for pupils of chorus club in elementary school, stdents of philharmonic club in senior high school and students in musical college in Japan.