A detecting apparatus includes: a light emitting element which emits light toward a detection material; a light receiving element which receives reflected light from the detection material; and an apparatus main body having an opening/closing member which opens and closes an opening through which light emitted from the light emitting element and reflected light from the detection material pass through, the apparatus main body being capable of moving between a first position where the apparatus main body comes into contact with the detection material and a second position where the apparatus main body separates from the detection material, and the opening/closing member being configured to open when the apparatus main body moves to the first position and to close when the apparatus main body moves to the second position.