In this paper, we demonstrate the dynamic OCT analysis of mental sweating of a few tens of eccrine sweat glands on a human fingertip. We propose a method for evaluation of the amount of excess sweat in response to mental stress, where the en-face OCT images of the spiral lumen of the eccrine sweat gland are constructed by data acquisition of the 128 B-mode OCT images. The dynamic analysis of mental sweating for sound stimulus is performed by the time-sequential piled-up en-face OCT images with the frame spacing of 3.3 sec. The amount of sweat of eccrine sweat glands was significantly increased corresponding to the strength of the sound stimulus.