[Problems]A gripping method for a turbocharger housing and a work gripping device that can accurately grip an inner diameter using a reference for shape during casting when processing.[Means for Solving Problems]In a gripping method of a turbocharger housing W, an end surface Y of a large diameter hole 22 facing a small diameter hole 25 is used for positioning in an axial direction. The inner diameter of the large diameter hole 22 is then gripped. A work gripping device 1 includes a cylindrical body 2, a plunger 3 that moves back and forth along an axial direction of the body 2, a jaw 4 that moves in a radial direction of the body 2 in tandem with the plunger 3, and a pusher 6 that presses the work W in a direction away from the body 2 in accompaniment with movement of the plunger 3. The jaw 4 includes a gripping surface 24 that grips the work W and a contact surface 5 that projects in an outward radial direction from an end edge of the gripping surface 24 away from the body 2. The pusher 6 presses the work W to the contact surface 5 and the work W is gripped.