In order to secure printing quality, a head unit includes a thermal head having a heating body formed on one surface of a glass substrate made of a transparent glass material, the heating body being configured to generate heat when supplied with external power, and a support body is laminated onto the glass substrate in a stacked state. The glass substrate and the support body include a plurality of lamination reference marks and a plurality of head positioning reference marks, respectively, which are disposed so as to be mutually aligned in a direction along the one surface of the glass substrate.