In order to study the application of a new type of aggregates made from fly ash for prestressed concrete structures, the authors prepared prestressed concrete beam specimens and carried out 1) bending tests, 2) shear tests and 3) stress measurement of prestressing strands. The results show that prestressed concrete beams used the aggregates have few structural problems and the aggregates can be applied to prestressed concrete structures. Moreover, the material properties of concrete used the aggregates made from fly ash were also investigated.