Abstract: A crankshaft phase indexing apparatus of this invention is provided with a pair of spindles arranged in alignment with a first axis. The Spindles are rotated respectively by a pair of spindle driving motors, which are controlled to rotate at the same speed. Chucks are mounted to the respective spindles. The chucks hold ends of a crankshaft in alignment with a second axis, which is displaced from and parallel to the first axis. A phase conversion shaft is rotatably arranged in at least one of the chucks in alignment with the second axis. The phase conversion shaft is connected to the crankshaft for rotating the crankshaft to permit phase indexing of crankpins of the crankshaft into axial alignment with the first axis. A phase indexing shaft, which is coupled to the phase conversion shaft, is located concentrically with the spindles and is rotated by a phase indexing motor.