This paper deals with the analysis for the long-term behavior due to continuity of composite precast concrete girder bridges and the analysis includes the section and member analyses. On the bases of taking the layer approach dividing a section with imaginary steel and concrete layers and using the assumed displacement field formulation the stiffness matrix of a beam element is derived. Besides, the iteration method adopted is the combined constant-variable method, i.e., the stiffness matrix is only updated at every loading step. Creep and shrinkage strains at each layer are calculated by using the first-order algorithm based on the expansion of creep compliance because the stress variation can be considered effectively. Finally numerical examples are analyzed with the objective to predict the long-term behavior of the bridge according to the difference in ages of concrete used in decks, girders and continuity parts and the steel ratio at the continuity part.