purpose This study was to investigate the effect that the trunk stability strengthening exercise of patient with stroke had on trunk control and spinal alignment. Methods The subjects were 22 patients with a stroke, 13 subjects were allocated to the trunk stability strengthening exercise group, other 9 subjects ordinary exercise group respectively. And the trunk stability strengthening exercise was carried out for a total of 10 weeks. This study used TIS, PASS, and FES to assess trunk control. And used 4D Formetric to measure the spinal alignment. Results The results of this study are as follows. Firstly, there was a significant difference in the trunk control through the trunk impairment scale in the exercise group. Secondly, there was a significant difference in the trunk control through the postural assessment scale for stroke in the exercise group. Thirdly, both groups, there was a significant difference in basic activities of daily living, instrumental activities of daily living through Falls Efficacy Scale. And between the groups, there was significant difference. Fourthly, both groups, there was no significant difference in spinal alignment. And between the groups, there was no significant difference. Fifthly, it was shown that there was a correlation between trunk control and fall efficacy. Besides, spinal segment rotation angle showed a correlation with trunk impairment scale, postural control assessment, and fall efficacy. And the scoliotic curvature also showed a correlation with postural control assessment. Conclusion In conclusion, the 10-weeks trunk stability strengthening exercise program was effective in improving trunk control of patient with a stroke. The results, it is thought that various studies on the exercise program effective in the spinal alignment will be required for clinically improving trunk control of patient with a stroke.