Provided is a magnetic particle holding carrier enabling automatization of treatment of a biological substance such as a protein by improving dispersibility of nano-size magnetic particles and suppressing nonspecific adsorption onto the wall of a container such as a pipette tip without damaging the properties of the nano-size magnetic particles such as a large solid-phase area and ability to arbitrarily design a functional protein, and provide a method for preparing the same. The magnetic particle holding carrier is formed of a micro-size nonmagnetic carrier and a plurality of nano-size magnetic particles bound to the carrier.