A two-shaft extruder comprising: a pair of rotor shafts (1, 1a, 1b) rotatably disposed with a distance therebetween diminishing toward the leading ends thereof; and a screw blade (2, 2a, 2b) mounted to the leading end of each one of the pair of rotor shafts, one screw blade intruding into the pitch of the other screw blade; and a drive unit mounted the base end of each one of the pair of rotor shafts for rotatably driving the rotor shaft associated therewith without the use of conical gears for synchronizing the drive of the pair of rotor shafts; wherein there is provided a screw blade contact presenting mechanism configured to allow a predetermined phase difference between the pair of rotor shafts, while inhibiting a phase difference greater than the predetermined phase difference when the pair of rotor shafts are rotatably driven respectively; wherein said screw blade contact preventing mechanism includes: a first abutment member comprised of a plurality of projecting portions formed in one rotor shat along the peripheral direction thereof and equidistantly or substantially equidistantly from each other; and a second abutment member comprised of a plurality of projecting portions formed in the other rotor shaft along the peripheral direction thereof and equidistantly or substantially equidistantly from each other; a path of the projecting portions of the first abutment member and a path of the projecting portions of the second abutment member are configured to interfere with each other; and between a projecting portion of the first abutment member and a projecting portion of the second abutment member peripherally opposed thereto, there is provided a gap (d) for allowing the predetermined phase difference between the pair of rotor shafts, while inhibiting a phase difference greater than the predetermined phase difference; wherein a plurality of sets of the first abutment members and the second abutment members are provided along the longitudinal direction of each rotor shaft; the projecting portions (6a1, 6a2,...) of the first abutment member belonging in a certain set are made different in position peripherally as seen in the axial direction of the one rotor shaft than the projecting portions (6a1, 6a2,...) of the first abutment member belonging in another set adjacent thereto; and the projecting portions (7a1, 7a2,...) of the second abutment member belonging in a certain set are made different in position peripherally as seen in the axial direction of the other rotor shaft than the projecting portions (7a1, 7a2,...) of the second abutment member belonging in another set adjacent thereto. a pair of rotor shafts (1, 1a, 1b) rotatably disposed with a distance therebetween diminishing toward the leading ends thereof; and a screw blade (2, 2a, 2b) mounted to the leading end of each one of the pair of rotor shafts, one screw blade intruding into the pitch of the other screw blade; and a drive unit mounted the base end of each one of the pair of rotor shafts for rotatably driving the rotor shaft associated therewith without the use of conical gears for synchronizing the drive of the pair of rotor shafts; wherein there is provided a screw blade contact presenting mechanism configured to allow a predetermined phase difference between the pair of rotor shafts, while inhibiting a phase difference greater than the predetermined phase difference when the pair of rotor shafts are rotatably driven respectively; a first abutment member comprised of a plurality of projecting portions formed in one rotor shat along the peripheral direction thereof and equidistantly or substantially equidistantly from each other; and a second abutment member comprised of a plurality of projecting portions formed in the other rotor shaft along the peripheral direction thereof and equidistantly or substantially equidistantly from each other; a path of the projecting portions of the first abutment member and a path of the projecting portions of the second abutment member are configured to interfere with each other; and between a projecting portion of the first abutment member and a projecting portion of the second abutment member peripherally opposed thereto, there is provided a gap (d) for allowing the predetermined phase difference between the pair of rotor shafts, while inhibiting a phase difference greater than the predetermined phase difference;