There are little execution results of seismic retrofit of large-scale bridges such as arch bridge. In a deck type arch bridge very big up-lift forces for bearing supports and section forces beyond yield stresses for many members occur during an large earthquake. Therefore, an effective seismic retrofit design should be discussed to reduce dynamic response by nonlinear dynamic analysis using fiber element. For an target arch bridge of spandrel arch bridge with 214m span length, five independent retrofit countermeasures are proposed, and three effective plans from those are extracted. Furthermore these three plans are put together to make one superior plan. In evaluation of seismic safety of each member, importance of the member and mechanism of the damage are considered.