Abstract Different factors can develop trust in firms. Considering intra-organizational theories in this field, the research investigates the factors with a comparative approach between family and non-family firms. The research uses survey methods. Research census is family and non-family firms in Soleyman Sabahi Industrial City Town. According to poll, all active family and non-family firms were interviewed. 3 laborer questionnaires and 1 firm owner questionnaire were distributed in each firm. Totally, 163 family and 153 non-family firms were investigated. Multi group analysis was done by Mplus software. Total sample analysis provided an adequate fit to the data; there is significant difference among groups for the theoretical model. Also rate of trust explanation in family firms is 71 percent.