• Japan has a high suicide rate but concerningly low use of professional services • Beliefs, attitudes and intentions for help seeking for suicidal ideation were examined • High suicide literacy, low stigma, and low self-reliance associated with more positive attitudes • Specific subgroups of the Japanese population with increased risk were identified • There is a need to develop public health messaging to increase professional service use Despite high suicide rates in Japan, many people do not seek professional help for suicidal thoughts. We identified modifiable factors associated with help-seeking beliefs, attitudes, and intentions for suicidal ideation, and examined characteristics associated with suicidal ideation. Participants were 217 Japanese adults recruited online. We assessed beliefs, attitudes and intentions regarding professional help seeking, and recent suicidal ideation. Greater suicide exposure and less social support were associated with more negative help-seeking beliefs. More positive help-seeking attitudes were associated with less education, no religious affiliation, greater suicide literacy, lower suicide stigma, and lower self-reliance. No significant correlates of help-seeking intentions were identified. Recent suicidal ideation was associated with non-binary gender, less education, negative beliefs/attitudes towards help-seeking, poorer mental health, lower mastery, less social support, greater self-reliance, and greater suicide normalisation. Interventions to improve help-seeking in Japan emphasise the limits of self-reliance, and increase knowledge around suicide prevention and professional psychological services.