A hinge assembly includes a first body, and a second body capable of rotating relatively to the first body. The first body includes a first main part and a pair of stopper portions respectively extending from two sides of the first main part and coplanar with the first main part. Two ends of a shaft are fixed with the pair of stopper portions, respectively. The second body includes a second main part, a pair of blocking portions and a resilient arm located between the pair of the blocking portions. When the second body rotates to be perpendicular to the first body, the second body is positioned stably relative to the first body without an external force, due to an elasticity of the resilient arm of the second body.