A puncture needle configured to be inserted in an ultrasound endoscope (1, 100) having a bendable part capable of being operated to be bent, the ultrasound endoscope (1, 100) being configured such that a central axis extending from an outlet (24, 124) of an insertion channel substantially coincides with an ultrasound observation plane (10A, 110A), the puncture needle comprising: a sheath configured to be freely advanced or retracted in the insertion channel, the sheath being configured to be capable of being inserted into the insertion channel; a needle tube having an outer surface and an inner surface that forms an internal space extending along a longitudinal axis of the needle tube, the needle tube having a distal end opening which is in communication with the internal space at a distal end of the needle tube, the needle tube being capable of being inserted into the sheath; a wire having a proximal end and a distal end, the wire having elasticity such that the wire is restored to a wind shape in an absence of external force, the wire being stretched and loaded into the internal space of the needle tube against restoration to the wind shape such that the wire is supported by portions of the inner surface of the needle tube which are spaced apart from one another in a direction of the longitudinal axis of the needle tube; a slit part formed to open from the inner surface to the outer surface of the needle tube, the slit part having a pair of wall surfaces (34f-1, 34f-2) which are spaced apart from one another, the slit part having an opening width larger than an external diameter of the wire; and a stylet configured to push the proximal end of the wire loaded within the needle tube, wherein the needle tube has a needle tube curved shape part formed at a distal side of the needle tube, the needle tube curved shape part having elasticity such that the needle tube curved shape part is restored to a curved shape in an absence of external force, the needle tube has a needle tube distal part having a needle tip formed to be sharpened to puncture a tissue within a body cavity, the needle tube distal part being formed at a side more distal than the needle tube curved shape part, a section of the inner surface facing the slit part supports the wire within the needle tube, such that the wire is restored to the wind shape in the ultrasound observation plane (10A, 110A), the slit part is formed at the needle tube distal part such that the slit part is in communication with the distal end opening of the needle tube, and opens toward an inside of the curved shape of the needle tube curved shape part, and in a state that the needle tube projects from the insertion channel and the distal end of the wire is pushed from the slit part by the stylet, the pair of wall surfaces (34f-1, 34f-2) support the wire such that the wire is sandwiched between the pair of wall surfaces (34f-1, 34f-2). a sheath configured to be freely advanced or retracted in the insertion channel, the sheath being configured to be capable of being inserted into the insertion channel; a needle tube having an outer surface and an inner surface that forms an internal space extending along a longitudinal axis of the needle tube, the needle tube having a distal end opening which is in communication with the internal space at a distal end of the needle tube, the needle tube being capable of being inserted into the sheath; a wire having a proximal end and a distal end, the wire having elasticity such that the wire is restored to a wind shape in an absence of external force, the wire being stretched and loaded into the internal space of the needle tube against restoration to the wind shape such that the wire is supported by portions of the inner surface of the needle tube which are spaced apart from one another in a direction of the longitudinal axis of the needle tube; a slit part formed to open from the inner surface to the outer surface of the needle tube, the slit part having a pair of wall surfaces (34f-1, 34f-2) which are spaced apart from one another, the slit part having an opening width larger than an external diameter of the wire; and a stylet configured to push the proximal end of the wire loaded within the needle tube, wherein the needle tube has a needle tube curved shape part formed at a distal side of the needle tube, the needle tube curved shape part having elasticity such that the needle tube curved shape part is restored to a curved shape in an absence of external force, the needle tube has a needle tube distal part having a needle tip formed to be sharpened to puncture a tissue within a body cavity, the needle tube distal part being formed at a side more distal than the needle tube curved shape part, a section of the inner surface facing the slit part supports the wire within the needle tube, such that the wire is restored to the wind shape in the ultrasound observation plane (10A, 110A), the slit part is formed at the needle tube distal part such that the slit part is in communication with the distal end opening of the needle tube, and opens toward an inside of the curved shape of the needle tube curved shape part, and in a state that the needle tube projects from the insertion channel and the distal end of the wire is pushed from the slit part by the stylet, the pair of wall surfaces (34f-1, 34f-2) support the wire such that the wire is sandwiched between the pair of wall surfaces (34f-1, 34f-2).