Although several case reports have suggested a relationship between accessing Internet suicide sites and the incidence of suicide, the influence of the Internet on the incidence of suicide is not known. Thus, we examined the association between Internet suicide-related searches and the incidence of suicide in 20- and 30-year-old individuals in Japan. The Box-Jenkins transfer function model was applied to monthly time series data from January 2004 to May 2010 (77 months). The terms "hydrogen sulfide," "hydrogen sulfide suicide," and "suicide hydrogen sulfide suicide" at (t-11) were related to the incidence of suicide among people aged in their 20 s (P = 0.005, 0.005, and 0.006, respectively) and people aged in their 30 s (P = 0.013, 0.011, and 0.012, respectively). "BBS on suicide" at (t-5) and "suicide by jumping" at (t-6) were related to the incidence of suicide in people aged 30-39 (P = 0.006 and 0.001, respectively). Internet searches for specific suicide-related terms are related to the incidence of suicide among 20- and 30-year-old individuals in Japan. Routine interrogation by a clinician about visiting Internet suicide websites and stricter regulation of these websites may reduce the incidence of suicide among young people.