We recorded the auditory-evoked magnetic fields from children and adults with absolute pitch during the following tasks: (1) hearing 1000 Hz pure tones inattentively, (2) hearing eight random tones inattentively and (3) listening to eight random tones and identifying each tone. In children with absolute pitch, there was no significant positive correlation between the appearance rate of N100m and the kinds of tasks. In adults with absolute pitch, only the right N100m dipole moments increased significantly in tasks (1) and (2). The present results suggest that the circuit for labeling in the right auditory cortex may lose a function from childhood to adulthood, which reveals neuroplasticity in the development of absolute pitch ability.