The present invention discloses an eye motion sensing method, a flexible contact body, an external sensing coil, and a system. The method may include: sensing an eye motion by using a servo motion signal of a permanent magnet implanted into a flexible contact body; applying at least four coils disposed externally on a same plane, and monitoring a servo motion of the permanent magnet according to an electromotive force in the coils; and converting the electromotive force to restore an eye motion signal. The present invention can use the sensing coils distributed around an eyepit to detect the electromotive force generated when the eye motion leads to the servo motion of the flexible contact body, and analyze the electromotive force. Accordingly, the eye motion triggered by a perceptual task can be analyzed objectively.