In the present paper, we study the existence and uniqueness of the solution for multi-term fractional boundary value problem under Riemann-Liouville fractional operators by using Banach's fixed point theorem. Afterward, we investigate some existence results for a semilinear fractional differential inclusions multi-term problem by using some notions and properties on set-valued maps together with classical fixed point theorems due to Leray-Schauder. The cases when the set-valued function has convex as well as nonconvex values are considered. Finally, some examples are given to illustrate our main results.