Abstract: An automatic piston inserting equipment comprises a block positioning means for positioning a cylinder block B to a piston inserting position, a piston positioning means for moving and positioning a piston P with a connecting rod R for insertion thereof into a cylinder bore formed in the cylinder block B vertically from above, a cap positioning means for moving and positioning a connecting rod cap C to clamp it vertically from below to the connecting rod R inserted into the cylinder bore, a clamp means for clamping the connecting rod cap C to the connecting rod R, and a vision system. The vision system detects central position coordinates of the cylinder bore lying at the piston inserting position and central position coordinates of the piston P lying at a start-point chuck position, and on the basis of both such central position coordinates calculates a movement quantity for insertion of the piston P into the cylinder bore.