  We complete the N=1 superfield action for the generic system of vector
multiplets and hypermultiplets coupled to 5D supergravity, which is based on
the superconformal formulation. Especially we clarify the gravitational
couplings to the bulk matters at linear order in the gravitational superfields.
They consist of four N=1 superfields, two of which are Z_2-odd when the fifth
dimension is compactified on S^1/Z_2. This formulation provides a powerful tool
to calculate quantum effects, keeping the N=1 off-shell structure.
