Abstract: To provide a spindle stage for testing a magnetic head in which high precision servo following can be performed by an inexpensive VCM mechanism without using a piezoelectric element, and to provide a device for mounting/demounting a magnetic head automatically. In a spindle stage for testing a magnetic head which includes: a head arm device having a head arm portion which is driven to swing by a VCM mechanism; and an HGA attached to the head arm portion, and loads the head arm device and the HGA relative to a surface of a medium in rotation to measure the electrical and mechanical characteristics, wherein the spindle stage includes: a fitting portion in which a swaging boss of the HGA is removably fitted; and a clamping member which moves between a locking position in which the swaging boss fitted in the fitting portion is locked and a releasing position in which the swaging boss can be freely fitted and removed into and from the fitting portion.