Objectives: The purpose of this study was to investigate the differential performance on musical chord and grammaticality judgement tasks in post-stroke aphasia. The accuracy of musical chord judgement task and grammaticality judgement tasks were analyzed, and the correlation between grammaticality judgement task and the severity of aphasia was examined. Methods: Fourteen individuals with aphasia and fifteen adults without aphasia participated in the study. The subject listened to a presented voice and was asked to determine whether the musical chord connection was natural and whether there was a grammatical error in the sentence. Results: First, People With Aphasia (PWA) showed significantly lower accuracy in the grammaticality judgement task compared to adults without aphasia. Second, PWA showed significantly lower accuracy in the musical chord judgement task compared to adults without aphasia. Third, the accuracy of the grammaticality judgement task was the most predictable variable of the severity of aphasia by 37.9%. Conclusion: PWA showed significantly lower accuracy in musical chord and grammaticality judgement tasks compared with normal adults, suggesting that PWA have difficulties in performing musical and grammatical tasks. Since damage to the brain structures affects music and language ability, PWA showed poorer performance on both musical chord and grammaticality judgement tasks. Moreover, grammaticality in Korean has an important role in this task. Thus, producing various treatment protocols of grammar comprehension is important because grammaticality is an important linguistic feature in comprehending sentences in Korean.