This study aimed to investigate difficulties experienced by nursery school staff in involving parents with mental health disorders and their children. Semi-structured interviews were conducted with six staff members of nursery schools who cared for children whose parents had mental health disorders regarding the difficulties faced when caring for such children and involving their parents. The findings of the semi-structured interviews were then inductively analyzed. The following difficulties were revealed: “It is hard to communicate with parents due to symptoms of parent’s disease,” “Staff experiences fear owing to parents’ behavior caused by their disease,” “Arranging support system to parents is difficult,” “I do not know the way care is adjusted according to parents’ condition and treatment,” “Feeling burdened by the impact of inadequate parenting on their children,” “Avoiding and dealing with problems with other parents and children is difficult,” “Developing child care and the nursery school system are difficult because of the need to deal with parents” and “Cooperating with other organization is difficult.” Establishing opportunities for education concerning care according to the disorder and treatment, support for mental health among staff, and supporting cooperation with other organizations were suggested to improve the condition of parents and the health of children, while reducing the difficulties of nursery staff.