A syringe needle assembly comprising: syringe needle having a needle tip formed on a front end thereof; and a safety tube covering the syringe needle, coupled to a rear end of the syringe needle and opened in an injection direction of the syringe needle, wherein, when the syringe needle is inserted into skin, the safety tube is contracted towards a rear side of the needle tip, and when the syringe needle is pulled out from the skin, the safety tube is extended towards a front side of the needle tip, wherein the safety tube comprises: a deformation part configured to be elastically deformed when the syringe needle is inserted into the skin or pulled out from the skin; and a fixing part configured to support the deformation part in the longitudinal direction of the syringe needle, wherein the syringe needle assembly further comprises: a slider formed to be movable along the outer circumferential surface of the safety tube, and in a case where the slider part is positioned on the outer circumferential surface of the deformation part, the inner circumferential surface of the slider compresses the outer circumferential surface of the deformation part when the deformation part is elastically deformed, characterized in that an inclined member is formed on the front end portion of the safety tube, the inclined member having an outer diameter which increases along the injection direction of the syringe needle and an inner diameter which is reduced when the slider is positioned on an outer circumference of the inclined member, and wherein an engagement recess or an engagement hole is formed on the slider, and a protrusion is formed on the front end portion of the safety tube to be inserted and engaged in the engagement recess or the engagement hole when the slider is positioned on the outer circumferential surface of the inclined member. syringe needle having a needle tip formed on a front end thereof; and a safety tube covering the syringe needle, coupled to a rear end of the syringe needle and opened in an injection direction of the syringe needle, wherein, when the syringe needle is inserted into skin, the safety tube is contracted towards a rear side of the needle tip, and when the syringe needle is pulled out from the skin, the safety tube is extended towards a front side of the needle tip, a deformation part configured to be elastically deformed when the syringe needle is inserted into the skin or pulled out from the skin; and a fixing part configured to support the deformation part in the longitudinal direction of the syringe needle, a slider formed to be movable along the outer circumferential surface of the safety tube, and in a case where the slider part is positioned on the outer circumferential surface of the deformation part, the inner circumferential surface of the slider compresses the outer circumferential surface of the deformation part when the deformation part is elastically deformed, characterized in that an inclined member is formed on the front end portion of the safety tube, the inclined member having an outer diameter which increases along the injection direction of the syringe needle and an inner diameter which is reduced when the slider is positioned on an outer circumference of the inclined member, and wherein an engagement recess or an engagement hole is formed on the slider, and a protrusion is formed on the front end portion of the safety tube to be inserted and engaged in the engagement recess or the engagement hole when the slider is positioned on the outer circumferential surface of the inclined member.