A turbine includes: a housing including an accommodating portion accommodating a turbine impeller; a first turbine scroll flow path communicating with the accommodating portion; a second turbine scroll flow path communicating with the accommodating portion and having a volume larger than a volume of the first turbine scroll flow path; a valve seat having a first port and a second port, the first port communicating with the first turbine scroll flow path, the second port communicating with the second turbine scroll flow path and having an opening area smaller than an opening area of the first port; a valve configured to contact the valve seat; and a shaft holding the valve and arranged on a side opposite to the first port with respect to the second port.