An electric reciprocation generator provided with a dental reamer including a flexibly bendable needlelike part and a supporting shaft, the electric reciprocation generator comprising: a housing ; a vibration tube having a pin hole provided in a side surface thereof; wherein the vibration tube is provided inside the housing so as to be capable of vibrating in a forward-backward direction; a reciprocation generation unit constructed by a micro-motor , a rotating shaft connected to the micro-motor , and a pin provided eccentrically at the tip of the rotating shaft and engaged with the pin hole of the vibration tube the pin hole being circular and slightly larger than the pin ; and a screw cap detachably screwed to a rear end part of the vibration tube ; characterized in that a reamer mounting opening opens at the rear end part of the vibration tube , and when the reamer is mounted from the reamer mounting opening , the reamer is configured to be capable of being pushed in until the needlelike part slips out of a needle-through hole formed in a distal end flange of the vibration tube and a distal end part of the insertion part comes into contact with the distal end flange of the vibration tube , the screw cap is adapted to be screwed into the reamer mounting opening , and for fitting the reamer to the vibration tube in contact with a rear end of the insertion part of the needlelike part , and the pin hole is engraved at an outer peripheral part of the vibration tube in such a way as to have a play for the pin to allow the vibration tube to perform a pivoting motion and an engraving angle is less than the entire circumference, or an obstructive protruding part is provided inside the pin hole against which the pin abuts. a housing ; a vibration tube having a pin hole provided in a side surface thereof; wherein the vibration tube is provided inside the housing so as to be capable of vibrating in a forward-backward direction; a reciprocation generation unit constructed by a micro-motor , a rotating shaft connected to the micro-motor , and a pin provided eccentrically at the tip of the rotating shaft and engaged with the pin hole of the vibration tube the pin hole being circular and slightly larger than the pin ; and a screw cap detachably screwed to a rear end part of the vibration tube ; characterized in that a reamer mounting opening opens at the rear end part of the vibration tube , and when the reamer is mounted from the reamer mounting opening , the reamer is configured to be capable of being pushed in until the needlelike part slips out of a needle-through hole formed in a distal end flange of the vibration tube and a distal end part of the insertion part comes into contact with the distal end flange of the vibration tube , the screw cap is adapted to be screwed into the reamer mounting opening , and for fitting the reamer to the vibration tube in contact with a rear end of the insertion part of the needlelike part , and the pin hole is engraved at an outer peripheral part of the vibration tube in such a way as to have a play for the pin to allow the vibration tube to perform a pivoting motion and an engraving angle is less than the entire circumference, or an obstructive protruding part is provided inside the pin hole against which the pin abuts. <EOS>