Abstract: Provided is a magnetic tape device including: a magnetic head having a magnetic element that acts in proximity to a magnetic layer formed on a front surface of a magnetic tape; and a support member which is disposed at a position facing the magnetic head and against which a back surface of the magnetic tape provided on a side opposite to the front surface is pressed, in which the support member has a groove formed along a running direction of the magnetic tape only in a region corresponding to a non-acting region except for a region of the magnetic layer on which the magnetic element acts.