The present invention is a puncture apparatus with an automatic puncture function, that includes: a hollow needle tube a flexible sheath having the needle tube inserted therethrough a main body having one of the ends of the sheath fixed thereto a slider attached to the main body, the slider being capable of sliding in an axial direction relative to the main body a needle tube-maneuvering section, attached to the slider, capable of sliding in an axial direction relative to the slider, the needle tube-maneuvering section having an end section of the needle tube fixed thereto a retraction state-maintaining member for maintaining the needle tube-maneuvering section in the retracted state toward a proximal end an urging member, provided in the needle tube-maneuvering section, for urging a retracted state of the needle tube-maneuvering section toward the distal end an operation section for resetting the operation of the retraction state-maintaining member releasing the ejection force and projecting the needle tube-maneuvering section toward the distal end and an unintentional operation preventive member, provided to the slider, for holding the operation section in an non-operating state, wherein the non-operating state of the operation section held by the unintentional operation preventive member can be reset only when the distal end of the needle tube is exposed by sliding the slider to a predetermined position relative to the main body.
