The flow path switching device includes: a body 100 including an outer cylinder 101 having four ports 111 and a plug 102 having two arc-shaped tunnel-like flow paths 121 each connecting adjacent two of four openings 102a formed in a side surface of the plug 102. The plug 102 is rotatable between a first position and a second position, the first position being a position in which one of the flow paths 121 connects adjacent two of the four ports 111 and the other flow path 121 connects the remaining two ports, and the second position being a position in which each of the flow paths connects adjacent two of the ports 111 which are not connected when the plug 102 is located at the first position.
