A hinge assembly for use in a flat display monitor includes a support member, a rotational base and a pivot mechanism for rotatably connecting the rotational base to the support member. The support member includes two first sidewalls, a first resisting surface and a second resisting surface. Each first sidewall defines a pivoting hole. The pivot mechanism includes a pivotal shaft, a limiting washer and a fixing element. The pivotal shaft includes a shaft portion running through the pivoting bole. The pivotal shaft is non-rotatable relative to the support member. The limiting washer includes a first restricting surface and a second restricting surface. The limiting washer is non-rotatable relative to the rotational base with the first restricting surface and the second restricting surface configured for resisting the first resisting surface and the second resisting surface respectively.