External magnetic field is usually applied to the superconducting wire which is used for superconducting machines. Phases of the external field and self field are generally not the same. This difference of the phases is known to do an important role in the generation of the AC loss. The AC loss is influenced mainly by longitudinal magnetic field component which is generated by the twisted-structure of the filament and strand. This paper describes the AC loss of an AC superconducting wire in combined action of an AC transport current and AC magnetic field for various phase differences. Experimental results are compared with calculated results.