[Background] Although many patients complain of eye fatigue caused by accommodative spasm, there have been no reports of a good objective examination method to diagnose it. [Purpose] The spectral power of the high frequency component of the accommodative microfluctuation (spectral power of HFC) differs according to the constrictive degree of the accommodation. In this paper, we expatiated upon our previously reported analyzing processes of the spectral power of HFC, and we investigated the relationship between normal subjects and subjects with asthenopia. [Method] The accommodative microfluctuation were recorded when the subjects were looking at a stable target. The waves of the accommodative microfluctuation were analyzed by FFT. [Results] The spectral power of HFC for the distant target was 50-60 in the subjects with normal vision, but it was higher in the subjects with asthenopia. [Conclusion] Our results suggested that the ciliary muscle was also actively working in asthenopia caused by accommodative spasm even if the patient was looking at a distant target.