A magnetic recording medium capable of suppressing the effects of thermal agitation and simultaneously reducing the average grain diameter and the standard deviation of magnetic crystal grains constituting a ferromagnetic metal film, without changing the film thickness of a metal under-layer or the film thickness of a ferromagnetic metal layer forming a recording layer, as well as a production method thereof, and a magnetic recording device. The magnetic recording medium includes a ferromagnetic metal layer of a cobalt based alloy formed on a base material with a metal underlayer having chromium as a major constituent disposed there between, wherein a seed layer having at least tungsten is provided between the base material and the metal under-layer, and the seed layer is an islands type film.