Heating reaction container comprises: a first member; a second member; and a third member. An opening is closed by the second member being detachably fitted in the first member and by the third member being detachably fitted in the second member. α1, α2, and α3 satisfy a relation of α3>α2>α1, α3=α2>α1, or α3>α2=α1, where α1 represents a thermal expansion coefficient of a first material of the first member, α2 represents a thermal expansion coefficient of a second material of the second member, and α3 represents a thermal expansion coefficient of a third material of the third member. A gap is present before heating, and a space is sealed, through the heating, by a first contact surface coming into intimate contact with a second contact surface and by a third contact surface coming into intimate contact with a fourth contact surface.