An exemplary hinge assembly (10) includes a base body (12), a bracket (14), a support board (18), a pivotal mechanism (16) and a rotational mechanism. The pivotal mechanism includes a pivotal shaft (163) fixed to the base body and rotatable relative to the bracket, an elastic member (165) and a fixing member (167). The rotational mechanism includes a rotational shaft (191), a rotary member (193), a steady member (195) and an elastic member (197). The support board and the rotary member are rotatable relative to the steady member, the base body, the bracket and the pivotal mechanism around a second axis. Each of the rotary member and the steady member defines an engaging surface (1932, 1951). One of the engaging surfaces forms at least one peak (1933), and the other of the engaging surfaces defines at least one valley (1953) corresponding to the peak.