Because management accountants contribute to the control process through providing performance reports that compare real results with planned outcomes for each responsibility center, building trust between this group of accountants who play a key role in the long-term success of the business unit, and the firm's managers, is one of the most important organizational issues. This research, using the qualitative research method and the field-based grounded theory approach, investigates the factors and conditions leading to building trust between managers and management accountants and accordingly it develops the relevant model. To answer the questions, this research uses results from interviewing 16 experts in this field. In 12th interview, we reached the saturation point in our findings. After initial coding of interviews and categorizing the various codes into basic themes based on the developed model, the research finds a set of Individual causal conditions such as competence, loyalty, and personality traits. Also it achieves organizational causal conditions such as team management and word-action fit; underlying factors such as organizational self-esteem, organizational culture; intervening conditions including the influence of location and time conditions on decisions; socio-cultural and economic-political factors; and strategies for transparency, loyalty, honesty, altruism, and job security. In addition, findings show that high morale, job satisfaction, and productivity improvement would be the consequences of building trust between managers and management accountants. Finally, using these findings, we are able to develop a manager and accountant trust model.