「doomo」 is a frequently used word in the daily life of Japanese people. No matter they need say hello or goodbye, and they want to thank somebody or apologize to someone, Japanese people often say this word. As a typical polysemy in Japanese language, How about the usage of doomo」? This paper aims to list all basic meanings of this word firstly, and then conclude the usage of it as an interjection on the basis of qualified the research scope.