A detection unit includes a first contact member that comes into contact with a surface of a recording material and a second contact member that comes into contact with the other surface of the recording material, and the first contact member and the second contact member face each other and are capable of nipping the recording material. The first contact member and the second contact member are movable in a direction in which the first contact member and the second contact member nip the recording material. The first contact member and the second contact member are rotatable about an axial line that extends in a direction in which the recording material is conveyed.