PROBLEM TO BE SOLVED: To provide a needle assembly of a novel structure with which the guide rod hardly rattles easily when the needle tip is protected in a protection position by the needle tip cover.SOLUTION: The needle assembly 10 has a moved side guide 64 engaged with a fixed side guide 30. The fixed side guide 30 has a guide groove 34 extending in the needle axis direction, while the moved side guide 64 has a longitudinal guide rod 65 guided by the guide groove 34. The guide rod 65 is fitted into the guide groove 34, and the portion of the guide rod fitted into the guide groove which is guided in the needle axis direction has a portion nonparallel to the needle axis direction. When the nonparallel portion of the guide rod 65 passes through the guide groove 34, a needle hole 16 is guided to a position which is deviated from the needle 12. When the needle cover 18 is moved to a position where the needle cover 18 covers the needle tip 20, the moved side guide 64 is held by the fixed side guide 30 in a direction perpendicular to the axis of the needle 12, to thereby prevent the needle tip cover 18 from moving in a direction in which the needle tip cover 18 deviates from the needle axis.SELECTED DRAWING: Figure 4
