Abstract: A method for measuring an amount of pain involves positioning a needle adjacent a non-human animal which is under anesthesia, inserting the needle at a controlled puncture speed into skin of the non-human animal, and measuring a muscle action potential of a muscle portion of the non-human animal produced by the insertion of the needle. The muscle action potential is measured from insertion start, at which the insertion of the needle into the skin is started, to insertion stop, at which the insertion of the needle into the skin is stopped.

Abstract: An object of the present invention is to provide an automatic injection device that allows setting of conditions of puncture according to the thickness of a syringe needle, the puncture depth, and so forth to reduce pain in the puncture and reduce the impact in the puncture to allow alleviation of anxiety and fear of a patient. An automatic injection device of the present invention has a syringe holder that holds a syringe attachably and detachably, a first drive unit that causes the syringe holder holding the syringe to advance to perform puncture by a syringe needle, and a control unit that controls the first drive unit to control the puncture speed.