Replacement-type blood-collecting device

A needle unit of a replaceable blood lancet device comprising a tubular barrel, the needle unit comprising:

• a tubular front slider inserted in the barrel and movable in the axial line direction, and comprising a front end partially exposed from an end portion of the barrel;
• and
• a needle carrier comprising a carrier body supporting a needle for blood collection to protrude in a front end direction and accommodated in the front slider movably in the axial line direction, a plurality of elastic transformation portions extending rearwards from the carrier body and elastically transformable inwards in a radial direction, and an interlocking holding protrusion protruding from the elastic transformation portion in a direction transverse to the axial line direction, held in a rear end of the front slider, and moving together with the front slider upon rearward movement.