A swirling flow generation device includes a first pipe having a first pipe axis and through which gas passes, a second pipe having a second pipe axis in a direction different from the first pipe axis and communicates with downstream of the first pipe, and an airflow changing unit provided in the first pipe and having an opening eccentric from the first pipe axis. A swirling flow is formed in the second pipe as the center of the airflow passed through the opening flows into the second pipe at a position that is eccentric from the second pipe axis.