The presence of excessive salt around root system disrupts water and nutrient uptake by root, causes inhibition of plant growth resulting in low plant yield. Arbuscular mycorrhizal (AM) symbiosis known for its mutualism towards plant by enhancing plant root growth. This study examined how AM symbiosis improved root growth and yield of rice plant under different salinity levels. The experiment was conducted in the screenhouse of Faculty of Agriculture, Universitas Gadjah Mada which arranged in a Randomized Complete Block Design (RCBD) with two factors. The first factor was rice plant that applied with and without arbuscular mycorrhizal inoculum. The second factor was four salinity levels at 0 dS m-1 (non-saline), 2.5 dS m-1, 5 dS m-1, 7.5 dS m-1. The results showed that the increase of salinity level treatment was followed by increasing of root Na content, resulting in decreasing of root growth as well as plant yield. Higher colonization rate in mycorrhizal plant than non-mycorrhizal plant caused two-fold increase in root cation exchange capacity (CEC). Under salinity, roots of mycorrhizal plant became longer and thicker, also root fresh weight did not decrease compared to non-mycorrhizal plant. By having higher root CEC and more extensive root, mycorrhizal plant was able to alleviate yield loss under 7.5 dS m-1 salinity stress.