A retort sterilization device 100 includes a heating pot 50 for accommodating retort food 70 and a water steam generation device 10 for generating water steam. The heating pot 50 is connected to the water steam generation device 10. The water steam generation device 10 has a liquid path 91 and a vapor path 92 independent from each other, and includes a heat exchanger 90 for performing heat exchange between liquid 25 flowing in the liquid path 91 and heating vapor flowing in the vapor path 92. The heating vapor is introduced into the vapor path 92 of the heat exchanger 90. A top end 91a of the liquid path 91 of the heat exchanger 90 is connected via a water steam supply pipe 12 to a water steam ejection section 52 located in an internal area 55 of the heating pot 50. The heat exchanger 90 is connected to a liquid container 20. A bottom end 91b of the liquid path 91 of the heat exchanger 90 is connected to the liquid container 20 via a communicating tube 30. The liquid container 20 is coupled to the heating pot 50.
