A magnet separator, comprising: a separator main body comprising a liquid storage part configured to store a liquid to be processed containing magnetic particles; and a magnet drum mechanism provided in the separator main body, wherein the magnet drum mechanism comprises: a cylindrical drum which is configured to rotate around a horizontal axis and comprises an upper portion configured to be exposed above a surface of the liquid; a magnet provided inside of the drum, facing an inner peripheral surface of the drum, and fixed to the separator main body in such a manner that the magnet is stationary when the drum is rotating, the magnet forming a magnetic field region configured to adsorb the magnetic particles in a circumferentially partial range of an outer peripheral surface of the drum; a liquid passage portion which is formed on a bottom side of the outer peripheral surface of the drum and through which the liquid is allowed to pass; and a scraper provided in a nonmagnetic field region formed on the upper portion of the drum at a position separated from the magnetic field region in the circumferential direction, the scraper being configured to guide the magnetic particles adsorbed onto the outer peripheral surface of the drum to an outside of the separator main body in the nonmagnetic field region, and the scraper comprises a front end portion which faces the outer peripheral surface of the drum in a contactless manner along an axial direction of the drum, and a gap is formed between the front end portion and the outer peripheral surface of the drum, characterized in that the scraper faces an upward area of the outer peripheral surface of the drum from an obliquely lower side, the upward area being located at a position having passed a top portion of the drum in a rotation direction of the drum. a separator main body comprising a liquid storage part configured to store a liquid to be processed containing magnetic particles; and a magnet drum mechanism provided in the separator main body, wherein the magnet drum mechanism comprises: a cylindrical drum which is configured to rotate around a horizontal axis and comprises an upper portion configured to be exposed above a surface of the liquid; a magnet provided inside of the drum, facing an inner peripheral surface of the drum, and fixed to the separator main body in such a manner that the magnet is stationary when the drum is rotating, the magnet forming a magnetic field region configured to adsorb the magnetic particles in a circumferentially partial range of an outer peripheral surface of the drum; a liquid passage portion which is formed on a bottom side of the outer peripheral surface of the drum and through which the liquid is allowed to pass; and a scraper provided in a nonmagnetic field region formed on the upper portion of the drum at a position separated from the magnetic field region in the circumferential direction, the scraper being configured to guide the magnetic particles adsorbed onto the outer peripheral surface of the drum to an outside of the separator main body in the nonmagnetic field region, and the scraper comprises a front end portion which faces the outer peripheral surface of the drum in a contactless manner along an axial direction of the drum, and a gap is formed between the front end portion and the outer peripheral surface of the drum, characterized in that the scraper faces an upward area of the outer peripheral surface of the drum from an obliquely lower side, the upward area being located at a position having passed a top portion of the drum in a rotation direction of the drum. a cylindrical drum which is configured to rotate around a horizontal axis and comprises an upper portion configured to be exposed above a surface of the liquid; a magnet provided inside of the drum, facing an inner peripheral surface of the drum, and fixed to the separator main body in such a manner that the magnet is stationary when the drum is rotating, the magnet forming a magnetic field region configured to adsorb the magnetic particles in a circumferentially partial range of an outer peripheral surface of the drum; a liquid passage portion which is formed on a bottom side of the outer peripheral surface of the drum and through which the liquid is allowed to pass; and a scraper provided in a nonmagnetic field region formed on the upper portion of the drum at a position separated from the magnetic field region in the circumferential direction, the scraper being configured to guide the magnetic particles adsorbed onto the outer peripheral surface of the drum to an outside of the separator main body in the nonmagnetic field region, and the scraper comprises a front end portion which faces the outer peripheral surface of the drum in a contactless manner along an axial direction of the drum, and a gap is formed between the front end portion and the outer peripheral surface of the drum, characterized in that the scraper faces an upward area of the outer peripheral surface of the drum from an obliquely lower side, the upward area being located at a position having passed a top portion of the drum in a rotation direction of the drum.