The purpose of this study is to examine the influence of institutionalization processes on the formation of relational norms in plural governance distribution channel contexts. The institutionalization processes were classified into regulative, certificative, and habitual institutionalization processes, and the six elements constituting these processes were specified. In the research model, coerciveness, inducement, authority, mimicry, imprinting, and bypassing were hypothesized to affect relational norms composed of flexibility, information exchange, and solidarity. The survey was conducted centering on independently owned gas stations, and hypotheses were tested using structural equation modeling. The results showed that coerciveness, inducement, mimicry, and imprinting had significant effects on the formation of relational norms, whereas authority and bypassing did not.