Purpose : The purpose of the study was to examine if a respiratory muscle strengthening training in patients with stroke can improve their pulmonary function. Methods : Volunteers were included for the study if a patient diagnosed stroke more than 6 months and had 24 points or higher in MMSE-K scores. Twenty-eight subjects participated in this study and were randomly divided into two groups; a breathing exercise group(n=14) and a control group(n=14). The intervention for all subjects was conducted for 20minutes, three times a week for 4 weeks. Subjects for the breathing exercise group had the respiratory muscle strengthening training using spiro-tigers, where-as subjects in the control group got their usual treatment ie a postural training. The six-minute walking test(6MWT) and the pulmonary function tests(FVC, $FEV_1$, $FEV_1$/FVC, VC, Vt, IRV and ERV) were employed to assess treatment effects at baseline and after their intervention. Results : Twenty-four subjects finished their 4-week treatment programs. The general characteristics between groups were found to be similar (p>0.05). The pulmonary function between groups were also observed no difference across groups at the baseline measurement (p>0.05). In the post treatment group comparison, subjects in the breathing exercise group showed an increase in lung function with VC ($2.73{pm}0.80{ell}$) and Vt ($0.87{pm}0.38{ell}$) than those in the control group ($1.91{pm}0.80{ell}$ and $0.48{pm}0.22{ell}$ respectively) (p<0.05). However, there was no difference found in 6MWT, FVC, $FEV_1$, $FEV_1$/FVC, IRV, and ERV across groups (p>0.05). Conclusion : A significant increase in VC and Vt was found in subjects with stroke, who had four-week training on respiratory muscle strengthening. However, respiratory muscle strengthening showed no effect on walking speed and FVC, $FEV_1$, $FEV_1$/FVC, IRV, and ERV in patients with stroke.