Turbocharging system

A turbocharging system includes a low pressure turbocharger (41) and a high pressure turbocharger (42); a cut-off valve (61) that cuts off communication between the outlet of a turbine of the high pressure turbocharger and the inlet of a turbine of the low pressure turbocharger; a high pressure side bypass (31) which bypasses the turbine of the high pressure turbocharger and the cut-off valve and introduces flowing fluid into the turbine of the low pressure turbocharger; a high pressure side bypass opening and closing valve (62) provided in the high pressure side bypass (31); a low pressure side bypass (32) which bypasses the cut-off valve and the turbine of the low pressure turbocharger and introduces the flowing fluid downstream of the turbine of the low pressure turbocharger; and a low pressure side bypass opening and closing valve (63) provided in the low pressure side bypass.