Purpose To clarify the sense of difficulty in mental health activities by occupational health nurses, as well as the characteristics of skills retention and future learning tasks.

Methods Self-administered questionnaire surveys were conducted. A cluster analysis was performed of 36 items regarding mental health activities, which were classified into categories. The years of experience were divided into 5 levels, i.e. 0–4 (novice), 5–9 (early–mid), 10–14 (late–mid), 15–19 (pre-management), and 20 or more years (late management), then the responses were compared between the 5 levels.

Results Mental health activities were classified into 6 categories, including the ‘construction of relationships of trust between workers and the manager, and data collection’, ‘assessment and support of individual consultations’, ‘support for job reinstatement and cooperation with relevant individuals within and outside of the enterprise’, ‘provision of information to workplace groups and organisations’, ‘construction of a mental health support system as a workplace organisation’, and ‘support for cases that are difficult to manage’. As the years of experienced increased, the number of nurses who had difficulty in their activities decreased. However, even in the management level, there was a strong sense of difficulty in ‘support for cases that are difficult to manage’. The sense of retaining skills increased with the increase in experience. With regards to future learning tasks, for all levels of experience many nurses indicated ‘support for cases that are difficult to manage’. Novices indicated ‘assessment and support of individual consultations’.

Discussion Suggestions for training measures according to each career level were obtained. Among novices, training is needed for the ‘assessment and support of individual consultations’, while for nurses in their early- to mid-career or after, ‘support for cases that are difficult to manage’ as well as focusing on group and organisational support was considered appropriate.