Objectives The purpose of this paper is to explain the relationship between experiential metaphors and multiword expressions that substitute for postpositional markers in Korean from the perspective of systemic functional linguistics. Methods grammatical metaphor, a concept introduced in Halliday (1985), operates in the opposite direction of metaphor to lexical metaphor. Whereas lexical metaphor starts at the lexical-grammatical level and realizes ‘alternative meanings’ at the discourse-semantic level, grammatical metaphor starts at the discourse-semantic level and realizes ‘alternative forms’ at the lexical-grammatical level. More specifically, circumstantial(or postpositional) metaphor is a phenomenon in which a multiword expression, such as phrase or clause, metaphorizes the meaning of a particular adverbial postposition, and has various lexicogrammatical alternative realizations. Here, the former circumstantial metaphoric expressions are called incongruent, and the latter adverbial postpositions are called congruent. Results The results of this study show that multiword expressions in Korean three different kinds: verbatim type, experiential metaphor type (Type I), experiential idiomatic type (Type II). Among these, the verbatim is only recognized as an entry stage for multiword expressions. After reviewing in detail the lists of previous studies (postpostion equivalents, postpostional collocation, periphrastic construction, grammaticalization, etc.), this paper applies the criteria of non-congruent, congruent, and postpositional meanings to them, and finally selects 34 experiential metaphors that substitute for postpositional markers and 13 idiomatic forms that replace postpositional markers. Conclusions Although we have limited our discussion to grammatical metaphors as substitution for postpositional markers, the scope of application of grammatical metaphors is very broad, and future research efforts need to continue to expand the scope.