This article examines how suicides influence suicide risks of others inJapan. Suicide contagion is the exposure to suicides or suicidal behaviorswithin one’s family, one’s peer group, or through media reports of suicidesand can result in an increase in suicide and suicidal behaviors. Previousstudies have shown that suicides or suicidal behaviors spread throughmedia reports of suicide and social ties. But, we have little empiricalevidence about the suicide contagion through social ties in Japanesesociety.Accordingly, we examine the effect of other’s suicides and suicideattempts on suicide ideation by analyzing web survey data. The analysisreveals that the exposure to suicides and suicide attempts within one’sfamily and one’s peer group influence suicide ideation risks. In contrast,suicide ideation risks are unaffected by suicide and suicide attempts of therelatives and acquaintances. Suicide risks hence spread through social tiesof family and peers. These results imply that social ties don’t alwaysprotective against suicide. It seems that social ties have a negative impacton human well-being.