An outer peripheral coating member contains first particles containing titanium oxide, second particles containing zirconium oxide, third particles containing niobium oxide or aluminum oxide, and a dispersion medium. It is preferable for the first particles to have at least two peak values R1 in a distribution of particle sizes of the first particles. One of the peak values R1 is within a range of 1 to 50 nm, and the other peak value R1 is within a range of 100 to 500 nm.