Abstract: A knife sharpener has a body with a handle. The body provides a knife blade support surface and an abrasive element support surface set at an included angle that is half a sharpening angle from the support surface. A permanent magnet is used to retain an abrasive element against the support surface of the body. The element may have a thin coating of abrasive material on a ferromagnetic strip having stiffening backing of a plastic. In use, a blade is laid on the support surface and urged away from the handle, while being pulled along the abrasive element. This action grinds into the material of the blade, leaving it with a sharp edge in due course.