Objective To examine the placebo response of sham repetitive transcranial magnetic stimulation (rTMS) for the treatment of primary insomnia.MethodsWe performed a comprehensive literature search for clinical trials evaluating the efficacy of rTMS addressing primary insomnia. To pool effect size estimates (Hedges′g) of active rTMS and sham rTMS across studies for outcome measures, a metaanalysis was done according to the Cochrane guideline. Results The rTMSsignificantly improved insomnia symptoms in active rTMS group, and the pooled effect size of Pittsburgh Sleep Quality Index (PSQI) was -1.44 (95% CI: -1.63, -1.26) (P＜0.001), and the relative risk (RR) of rTMS was 1.55 (95% CI: 0.90, 2.67) (P=0.11). The placebo response was also significant to reduce insomnia symptoms in sham rTMS group with Hedges′g of more than 0.8 for PSQI, SE, LPS, TST, and WASO. And 73.5% (95% CI: 50.8%, 96.2%) of the effect size of active rTMS was actually produced by sham rTMS.Conclusion RTMS is an effective method for the treatment of primary insomnia, but most of its effect amount is due to the effect of placebo (pseudo rTMS). The real rTMS effect only accounts for about 25% of the total treatment effect. The placebo effect increased with the prolongation of treatment time within 30 days. 