This study aims to find an adequate method to achieve opening a lid of Japanese tea caddy by robot arm. Although the lid is not screw structure, some people open the lid by screwing for opening. This paper compared two methods of opening the lid: by just pulling up the lid and by screwing the lid for opening. Opening ease of the lid was evaluated by using the maximum pulling up force for opening. To evaluate opening ease of the lid, the product of the time during opening the lid and the average pulling up force during the operation was also used. The lid opening operations by human was analyzed. The results show that 43.5% of people open the lid by screwing, and opening the lid becomes easy by screwing the lid. In addition, the lid opening operation was modeled, and the experiments of the operations were carried out by using robot arm. The experimental results show that the force caused by the decrease of the internal pressure of the container gives most influence on the force for opening the lid, and the lid is able to be opened with smaller force because screwing for opening the lid suppresses decrease of the internal pressure. It is concluded from these results that opening the lid becomes easy by screwing the lid for opening.