Disclosed is a substrate rotating device improved such that an amount of particle generation is remarkably reduced, and a substrate processing apparatus provided with the substrate rotating device. The substrate rotating device includes a driven rotary member, e.g., a driven ring, connected directly or indirectly to a substrate support member for supporting a substrate; and a driving rotary member, e.g., a drive rotor, that rotates in abutment against the driven rotary member to drive the driven rotary member for rotation. The driven rotary member and the driving rotary member are formed of ceramic materials, whose values of fracture toughness defined by JIS R1607 are different from each other, and/or whose values of three-point bending strength defined by JIS R1601 are different from each other.