Metal oxide powder formed of metal oxide particles, in which the metal oxide powder has first metal oxide particles having at least one protrusion portion and second metal oxide particles, the first metal oxide particles have an average primary particle diameter of 100 nm or more and 1,000 nm or less, the second metal oxide particles have an average primary particle diameter of less than 100 nm, and a fraction of a total mass of particles having a primary particle diameter of less than 100 nm in a total mass of the metal oxide powder is 0.3% by mass or more and 10% by mass or less.