Magnetoresistive device

A magnetoresistive device comprising a magnetoresistive element and a bias magnetic field generation unit, wherein

• the magnetoresistive element includes a free layer having a magnetization whose direction is variable by a magnetic field applied thereto,
• the bias magnetic field generation unit includes a ferromagnetic layer for generating a bias magnetic field to be applied to the free layer,
• the free layer has a first surface and a second surface located at opposite ends in a first direction, and a peripheral surface connecting the first surface and the second surface,
• the first surface is shaped to be long in a second direction orthogonal to the first direction,
• the ferromagnetic layer includes one or two main portions, a first side portion, and a second side portion,
• in a first cross section passing through a centroid of the first surface and parallel to the first and second directions, the one or two main portions are located on one side or opposite sides of the free layer in the second direction,
• in a second cross section passing through the centroid of the first surface and perpendicular to the second direction, the first side portion and the second side portion are located on opposite sides of the free layer in a third direction perpendicular to the first and second directions, and
• in the second cross section, a shortest distance between the peripheral surface of the free layer and the first side portion and a shortest distance between the peripheral surface of the free layer and the second side portion are 35 nm or less.