Background: The strong and continuous sternal compression recommended by Guidelines2015, but it cause to the burden on rescuer and it is difficult to carry it out by single rescuer for a long time. Purpose: We evaluated 2 minutes continuous chest compression only CPR on the senior woman who may have more often to perform bystander CPR alone at home. Material and methods: Sixty middle aged and older women were randomly divided into 3 group as follows. 1) continuous chest compression only group (as CCC group; n=20), 2) ten seconds pause group (10 seconds pause group; n=20): a group taking ten seconds pause followed by 30seconds continuous chest compression ,3) seven seconds pause group (7 seconds pause group; n=20): a group taking seven seconds pause followed by 30 seconds continuous chest compression. Results: Chest compression depth markedly decreased on the CCC group. The 10 seconds pause group did not reduce chest compression depth during the 2 minutes continuous compression, although the 7 seconds group reduced significantly chest compression depth. The 7 seconds pause group showed significantly higher total efforts expressed by the compression depth × time than those of 10 seconds groups. Conclusion: Seven seconds interruption every 30 seconds during 2 minutes continuous chest compression may maintain effectively quality of the chest compression while middle aged women perform chest compression alone.