A heating apparatus comprising a plurality of heat generation members (54b1 to 54b3), a plurality of contacts (54d1 to 54d4), a substrate on which the plurality of heat generation members (54b1 to 54b3) and the plurality of contacts (54d1 to 54d4) are mounted, and a switching unit (57a, 57c), the plurality of heat generation members (54b1 to 54b3) including a first heat generation member (54b1), and a second heat generation member (54b2) and a third heat generation member (54b3), a length of the second heat generation member (54b2) and a length of the third heat generation member (54b3) are shorter than a length of the first heat generation member (54b1) in a longitudinal direction of the substrate, wherein the plurality of contacts (54d1 to 54d4) includes: a first contact (54d1) to which one end of the first heat generation member (54b1) is connected, and a second contact (54d2) to which one end of the second heat generation member (54b2) and one end of the third heat generation member (54b3) are connected; a third contact (54d3) to which another end of the third heat generation member (54b3) is connected; and a fourth contact (54d4) to which another end of the first heat generation member (54b1) and another end of the second heat generation member (54b2) are connected, wherein the switching unit (57a, 57c) is configured to bring an electric path between the second contact (54d2) and the fourth contact (54d4) into one of a connecting state and an open state, characterized in that the first contact (54d1), the second contact (54d2), the third contact (54d3), and the fourth contact (54d4) are provided on end sides of the substrate beyond the first heat generation member (54b1), the second heat generation member (54b2) and the third heat generation member (54b3) in the longitudinal direction of the substrate, wherein the same number of contacts are provided in the both ends of the substrate. the plurality of heat generation members (54b1 to 54b3) including a first heat generation member (54b1), and a second heat generation member (54b2) and a third heat generation member (54b3), a length of the second heat generation member (54b2) and a length of the third heat generation member (54b3) are shorter than a length of the first heat generation member (54b1) in a longitudinal direction of the substrate, wherein the plurality of contacts (54d1 to 54d4) includes: a first contact (54d1) to which one end of the first heat generation member (54b1) is connected, and a second contact (54d2) to which one end of the second heat generation member (54b2) and one end of the third heat generation member (54b3) are connected; a third contact (54d3) to which another end of the third heat generation member (54b3) is connected; and a fourth contact (54d4) to which another end of the first heat generation member (54b1) and another end of the second heat generation member (54b2) are connected, wherein the switching unit (57a, 57c) is configured to bring an electric path between the second contact (54d2) and the fourth contact (54d4) into one of a connecting state and an open state, characterized in that the first contact (54d1), the second contact (54d2), the third contact (54d3), and the fourth contact (54d4) are provided on end sides of the substrate beyond the first heat generation member (54b1), the second heat generation member (54b2) and the third heat generation member (54b3) in the longitudinal direction of the substrate, wherein the same number of contacts are provided in the both ends of the substrate. a first contact (54d1) to which one end of the first heat generation member (54b1) is connected, and a second contact (54d2) to which one end of the second heat generation member (54b2) and one end of the third heat generation member (54b3) are connected; a third contact (54d3) to which another end of the third heat generation member (54b3) is connected; and a fourth contact (54d4) to which another end of the first heat generation member (54b1) and another end of the second heat generation member (54b2) are connected, wherein the switching unit (57a, 57c) is configured to bring an electric path between the second contact (54d2) and the fourth contact (54d4) into one of a connecting state and an open state, characterized in that the first contact (54d1), the second contact (54d2), the third contact (54d3), and the fourth contact (54d4) are provided on end sides of the substrate beyond the first heat generation member (54b1), the second heat generation member (54b2) and the third heat generation member (54b3) in the longitudinal direction of the substrate, wherein the same number of contacts are provided in the both ends of the substrate.