Processing device

The invention provides a processing apparatus which suppresses thickness deviation of a processed wafer. The processing apparatus includes: a holding unit that attracts and holds a wafer; a processing unit having a grinding wheel for grinding the wafer; and a processing liquid supply unit that supplies a processing liquid to the wafer, the holding unit having: a chuck table that holds the wafer; and a stage base for supporting the chuck stage, the chuck stage having: a porous plate having an adsorption surface for adsorbing a wafer; the frame body is arranged outside the adsorption surface in a surrounding manner; a cooling water path that is formed inside the housing and that allows cooling water to flow therethrough; a wafer suction hole which is formed in the frame body and transmits suction force to the suction surface of the porous plate; and a bolt hole that is formed in the frame body and fixes the chuck table to the table base, the table base having: a placement surface on which the lower surface side