The aim of the work is to study the regional investment policy of the agro-industrial complex development as one of the most important elements of the economic mechanism. At the present stage of the development of the Russian economy, the role of investments related to the modernization of the agro-industrial complex (agribusiness) is growing. The study of the problems of investment activity of agricultural enterprises is conditioned by the need to improve the theoretical and methodological foundations for stimulating business activity of agribusiness. The new agrarian policy should provide a breakthrough in improving the efficiency of agricultural production, primarily by switching to an innovative model for the development of agro-industrial enterprises. Regional investment policy affects the competitiveness of the agro-industrial complex, providing more attractive conditions for the development of the industry. Investment policy in the agrarian sector of the Republic of Mari El today is based on the principles of attracting invest-ments in efficient and competitive production and activities. The solution of the problem of increasing investment activity as a factor of economic growth and giving stability to positive shifts in the dynamics of investment in fixed assets is ensured by the market and the mechanism of regulatory influence of the state on investment and innovation processes. The need to improve the management of investment processes in order to increase the competitiveness of agricultural production is due to the solution of the tasks of import substitution and development of the export potential of the agroindustrial complex. A set of measures to improve investment and tax policy in the agrarian sphere was proposed. It is necessary to create a system of investor sup-port, an essential part of which can be a set of tax incentives for enterprises of the agroindustrial complex that are oriented towards innovative development and leading the country to an innova-tive model of economic growth. The implementa-tion of the proposed measures will promote the activation of investment activities in the agro-industrial complex and increase the level of import substitution in the Russian food market.