This research has investigated the impact of unusual transactions with related parties on the sensitivity of cash flow investment and financing, emphasizing the role of financial restrictions in the Tehran Stock Exchange during the period from 2014 to 2023, using the information of 125 selected companies. The results of the research hypothesis test, which was calculated by the generalized least squares method, indicated that unusual transactions with related parties through the granting of unusual credit and unusual sales increase the sensitivity of cash flow investment and financing, which indicates agency theory as well. The results showed that the presence of financial constraints increases and intensifies the positive relationship between unusual transactions with related parties and the sensitivity of cash flow investment and financing. In other words, according to the conflict of interest hypothesis (agency theory), unusual transactions with related parties cause the excess cash of the company to be misused opportunistically or in the form of financing by related parties and ultimately lead to Increase the sensitivity of cash investment and the company will suffer from financial restrictions. In their decisions, opportunistic managers act in conflict with the interests of shareholders and use cash flows to increase personal benefits and lead to an increase in investment sensitivity. to invest in ineffective projects and lead to an increase in the sensitivity of cash investment. Also, these people can increase the sensitivity of cash investment through reducing the quality of financial reporting and lack of sufficient disclosure regarding transactions with related parties.