In this study, we aim to achieve a robot motion to break an egg by a single robot arm. Eggs are often used for cooking. The study of the egg breaking by a dual arm robot has been done until now. We considered an adequate motion to break an egg by using a single robot arm. The arm makes a crack on the egg by hitting it to the edge of a frying pan, opens the shell of the egg by hooking it to the edge of the pan, and the content of the egg is dropped into the pan. We confirmed that this task was successfully executed only by using a single robot arm with the generated motion.