A pouch type secondary battery having enhanced reliability by protecting the battery from external impacts is described. A reinforcement structure may be installed on a pouch casing and an electrode assembly housed in the pouch casing. Short-circuits inside the pouch casing may be minimized. The pouch type secondary battery has an electrode assembly with positive and negative electrode plates with a separator interposed therebetween, and positive and negative terminal portions extending from the positive and negative electrode plates. A first reinforcement member is closely adhered to one or more planes of the electrode assembly. A second reinforcement member may be adhered to the pouch casing and used with or without the first reinforcement member.