A composite power generating device of the present invention includes an engine (110), a first flow line (121), a turbocharger (130), a second flow line (122), a third flow line (123), a compressor (211), a first medium line (221), a medium turbine (212), a second medium line (222), a working medium cooler (213), a recuperator (215), a power generating unit (214), a cross-line (233), a first heat exchanger (251), a second heat exchanger (252), and a third heat exchanger (253).