The article considers the theoretical and methodological foundations of assessing the investment security of the agricultural sector. Methodological approaches to the assessment of investment activity, investment potential and investment attractiveness have been studied, including: "Payback period (PP)"; "Discounted cash flows (NRV)"; "Internal rate of return (IIR)"; "Non-discounted rate of return (ARR)"; Net Present Value (NPV), Expected Net Present Value (ENPV), Sensitivity Analysis (SA), Risk-Adjusted Discount Rate (RADR) method. It is proved that these methods have their own advantages and disadvantages and do not always adequately reflect the interests of investors regarding the completeness of the assessment of investment attractiveness. In addition, many of the methods are very specialized and do not fully take into account the characteristics of investment attractiveness of different levels of the economic system: countries, industries, regions, enterprises and investment projects; they do not provide an integrated assessment of the aggregate content of investment attractiveness. It is proposed to assess the investment security of the agricultural sector by assessing its investment potential, which contains a set of interrelated components that may change over time; it is a dynamic system that can be influenced by certain actions, accordingly; it is appropriate to build an integrated indicator using the method of taxonomy, the use of which is determined by the complexity of the studied economic phenomena and processes, their versatility and ambiguity. The algorithm of formation of taxonomic indicator of investment potential of agrarian sector is resulted, the basic indicators which determine components of investment potential of agrarian sector are defined. In addition, the obtained result will provide a quantitative determination of the level of investment support of the agro-industrial sector of Ukraine, which will further determine the areas of improving the efficiency of investment support for the development of the agricultural sector.