In a coolant-cooled linear motor includes an armature including armature windings and a cooling jacket arranged to surround the armature windings, the cooling jacket unit includes four cooling jackets defining four side faces parallel to the extension direction of the armature and two end blocks defining two opposite end faces in the extension direction of the armature, the cooling jackets and the end blocks being connected to one another in a box shape. Each of the cooling jackets has an internal space to be supplied with a coolant; and a field magnet unit includes a yoke made of a ferromagnetic material and permanent magnets arranged in the yoke, one of the armature and the field magnet unit making relative movement with respect to the other.