The present paper attempts to explore a less-discussed topic, that is, 'self-deprecating' language used in conversation. Based on task-based conversations in Korean and Japanese, where speakers were told to arrange a series of picture cards to make a coherent story, this paper presents three examples of self-deprecation: (a) the use of self-directed negative yes/no interrogatives showing uncertainty or self-doubt, (b) self-deprecating digressions exposing one's weaknesses or personal issues, and (c) the collaborative nature of self-deprecation. Self-deprecating language, in which speakers lower or humble themselves toward their addressees, does not contribute to achieving the goal of communication according to the Western culture-based frameworks. It even deters the efficiency and automaticity constituting the objective of any interaction. However, the results of the analysis suggest that speakers often selfdeprecate in order to be on the same interactional plane, to be in equilibrium with each other. It is argued in this paper that, at least in some cultures, self-deprecating language is an important means that speakers use in conversation to level with each other and become of 'one mind'.