A safety needle assembly with a sheath, comprising: a hub including a proximal end connecting with a syringe and a distal end; a cannula including a proximal end connecting with the distal end of the hub, a lumen extending in a longitudinal direction of the cannula, and a distal end; a collar attached to the hub and having a sheath attachment part; a protector covering the distal end of the cannula by being attached to the hub or the collar, and being detachable to expose the distal end of the cannula; and an opening partially extending along at least a longitudinal direction of the sheath so as to house the cannula, wherein the sheath further comprises: a cannula fixing part (53, 57, 531) of fixing the cannula housed in the opening; an attachment part rotatably supporting the sheath in a direction of housing the cannula when the protector is detached to expose the distal end of the cannula, the attachment part being attached to the sheath attachment part of the collar; and a protrusive stopper arranged at a central portion of the sheath in a longitudinal direction in which the central portion is located at an opposite side of an aperture of the opening, or arranged at a position closer to the distal end of the sheath than the central portion, so that a finger of a user pushes the stopper of the sheath thereby to house the cannula in the opening, characterized in that the sheath comprises a circular recess used as a finger guiding region to which a finger of a user of operating the sheath contacts, the circular recess being arranged at a position closer to a proximal end side than the stopper located at an opposite side of an aperture of the opening, and a slope having a plurality of protrusions and recesses with large frictional resistance arranged between the circular recess and the stopper. a hub including a proximal end connecting with a syringe and a distal end; a cannula including a proximal end connecting with the distal end of the hub, a lumen extending in a longitudinal direction of the cannula, and a distal end; a collar attached to the hub and having a sheath attachment part; a protector covering the distal end of the cannula by being attached to the hub or the collar, and being detachable to expose the distal end of the cannula; and an opening partially extending along at least a longitudinal direction of the sheath so as to house the cannula, wherein the sheath further comprises: a cannula fixing part (53, 57, 531) of fixing the cannula housed in the opening; an attachment part rotatably supporting the sheath in a direction of housing the cannula when the protector is detached to expose the distal end of the cannula, the attachment part being attached to the sheath attachment part of the collar; and a protrusive stopper arranged at a central portion of the sheath in a longitudinal direction in which the central portion is located at an opposite side of an aperture of the opening, or arranged at a position closer to the distal end of the sheath than the central portion, so that a finger of a user pushes the stopper of the sheath thereby to house the cannula in the opening, a cannula fixing part (53, 57, 531) of fixing the cannula housed in the opening; an attachment part rotatably supporting the sheath in a direction of housing the cannula when the protector is detached to expose the distal end of the cannula, the attachment part being attached to the sheath attachment part of the collar; and a protrusive stopper arranged at a central portion of the sheath in a longitudinal direction in which the central portion is located at an opposite side of an aperture of the opening, or arranged at a position closer to the distal end of the sheath than the central portion, so that a finger of a user pushes the stopper of the sheath thereby to house the cannula in the opening, characterized in that the sheath comprises a circular recess used as a finger guiding region to which a finger of a user of operating the sheath contacts, the circular recess being arranged at a position closer to a proximal end side than the stopper located at an opposite side of an aperture of the opening, and a slope having a plurality of protrusions and recesses with large frictional resistance arranged between the circular recess and the stopper.