In these days, carbon fiber-reinforced polymer (CFRP) has been widely used for retrofitting and/or strengthening structural elements in structure. However, there are not enough test data to predict the long-term performance of the retrofitted structures exposed to weathering. The purpose of this study is to evaluate the effect of freezing and thawing on the structural performance of reinforced concrete (RC) beams strengthened in shear with carbon fiber sheet and plate. Seven small-scale RC beams (100 ㎜ × 100 ㎜ × 400 ㎜) were strengthened with CFRP in shear, subjected to up to 400 cycles freezing and thawing from -18~4℃, and tested to failure in four-point bending. The test data also indicated that no significant damage to carbon fiber sheet and plate strengthened concrete beams had occurred because of 400 cycles freezing and thawing.