Purpose : To analyze changes of the ocular components by dropping Cyclopentolate Hydrochloride(Cyclogyl 1 %). Methods : 95 Subjects were recruited but 6 subjects who have allergic reaction for any medicine and 21 mmHg over IOP were excluded to prevent any incidence that can take place in the middle of the test. Finally 89 subjects (age of 19.8±2.72 male 34. female 55. 110 eyes) participated in this test. Objective refraction. comeal curvature. anterior chamber depth and axial length were measured for this study. Results : After dropping Cyclogyl 1%, myopia and axial length decreased and anterior chamber depth increased significantly but no significant changes of comeal curvature and comeal astigmatism Even though the change of axial length was statistically significant. the value was slight. There were significant correlations between ACD and axial length(r = 0.639). ACD and SER( -0.434). ACD and comeal curvature(r = 0.164) and. axial length and SER(r = -0.822). axial length and comeal curvature(r = 0.498) under marufest refraction. Also there were sigruficant correlations between ACD and axial length(r = 0.592), ACD and SER(r = -0.416). ACD and corneal curvature(r = 0.158). Correlations between axial length and SER(r = -0.838), axial length and corneal curvature(r = 0.500) under cycloplegic refraction were significant too. ln case of the correlations between the difference of MR-CR ACD and MR-CR axial length, statistically significant correlations were found(r = 0.458) but not between the difference of MR-CR SER and MR-CR axial length, and the difference of MR-CR SER and MR-CR mean-K. Analyzing non-myopic subjects by gender. mean-K, ACD and axial length in male were greater than in female. And mean-K. ACD and axial length in myopic group were greater lhan in non-myopic group. Conclusion : As a result, spherical refraction. SER. ACD and axial length were changed significantly under cycloplegic refraction and change of ACD is found to be the main reason for changing refractive error.