【Introduction】Thumbtack needles for skin stimulation are used in the field of sports medicine. Their primary therapeutic mechanism is believed to be the increase in regional blood flow mediated by the axon reflex. However, it is not clear at this time whether a medical device (acupuncture device) for skin stimulation significantly increases regional blood flow at the stimulation site. Furthermore, sterile acupuncture needles in which the acupuncture needle body is inserted into the skin with multiple needles (hereafter referred to as Multi-core thumbtack needle) have not been manufactured to date, and their usefulness and potential application for blinding is unknown.【Materials and Methods】A single-blind randomized crossover trial was conducted in 16 healthy adult males. A multi-core thumbtack needle (needle length 0.55 mm, needle base diameter 0.3 mm, number of needles 37, pitch 1.0 mm, made of biosafe resin) was placed in the center of the palmar side of the forearm for 30 seconds, and then one week later they were randomly assigned in a 1:1 ratio to one group to receive stimulation in the same way with a sham needle (a flat disk made of the same material), or one group to receive stimulation in the opposite order. The primary endpoints were the change in regional blood flow (5 min post-stimulation vs. pre-stimulation) and the rate of change at the stimulation site, which were measured using a laser perfusion meter. The secondary endpoint was heart rate. A linear mixed model was used as the statistical method, with a significance level of 5%.【Results】Regarding the amount of change in regional blood flow, sham needles showed a mean of -0.09 (95% confidence interval [CI]: -0.39 to 0.21) mL/min/100g, whereas multi-core thumbtack needles showed a mean of 8.83 (95% CI: 5.86 to 11.79) mL/min/100g, indicating a significant intervention effect (P < 0.001), with no significant period effect (P = 0.474) or carryover effect (P = 0.441). There was no intervention effect on heart rate (P = 0.95).【Conclusion】A significant increase in local blood flow was observed with the use of the multi-core thumbtack needle employed in this study. As this response was not accompanied by a significant increase in heart rate, it is speculated that the effect is primarily mediated by the axonal reflex and the involvement of nitric oxide, as well as somatic-autonomic reflex mechanisms.