To provide a mass centering machining device capable of being adapted a plurality of kinds of workpieces having different dimensions.

This mass centering machining device 3 is provided with a holding unit for holding the workpiece Cs and a machining unit for opening a center hole in the workpiece Cs. The holding unit has a pair of receiving members 16 adjacently arranged in the horizontal direction to form a V-shaped receiving part 20 for receiving the workpiece Cs from a lower side, a clamping member 17 pressed by the workpiece Cs received by the pair of receiving members 16 from the above, and a moving mechanism 18 for individually and horizontally moving each of the receiving members 16 in an array direction X1 of the receiving members 16. The moving mechanism 18 is capable of adjusting a space of the pair of receiving members 16 in the array direction X1 and a position of each of the receiving members 16 in the array direction X1 by individually and horizontally moving each of the receiving members 16.