There is provided an adapter for blood sample dispensing which enables change of the presence and absence of a medicine to be mixed in a blood sample or the type of the medicine thereof while suppressing contact of blood with the air, during preparation of an examination sample, and a dispensing kit and a needle kit provided therewith. Dispensing is performed using an adapter 1 for blood sample dispensing which is mounted on a distal portion of a syringe and has a piping structure, in which the adapter has a fitting portion 3 fitted to the distal portion at one end, a nozzle portion 2 at the other end, and a flange portion 4 on an outer circumference surface, and in which the adapter 1 has a medicine 5, to be mixed in the blood sample S, on the inside of the nozzle portion 2.