Objective The study was designed to clarify relationships of family needs of mothers of school-aged children suffering from cerebral palsy with the parenting strain and mental health. Methods The subjects were 249 mothers of cerebral palsy children from schools for the physically handicapped in Japan. The survey item consisted of sex and age of the children and age, family needs, parenting strain, and mental health of the mothers. Family needs of the mothers were determined according to “The Family Needs Survey”. Parenting strain was assessed according to the “Parenting Strain Index for Parents with Disabled Children”. Mental health was measured according to “General Health Questionaire-12”. In the statistical analysis, an indirect model, with the parenting strain and family needs as the primary and secondary factor, respectively was postulated for mother's mental health, and fit of the model to the data was investigated. Results The Comparative Fit Index (CFI) was 0.962, the Tucker-Lewis Index (TLI) was 0.977, and the Root Mean Square Error of Approximation (RMSEA) was 0.058; these indices were statistically within the tolerance range. The path coefficient of correlation of the parenting strain with the family needs was 0.656, and the path coefficient of the parenting strain with mental health was 0.406; both were statistically significant. Conclusion Relationships between family needs of mothers of cerebral palsy children from schools for the physically handicapped children and the mothers' parenting strain and mental health were indicated. The findings suggested that in order to develop and implement social intervention strategies for reducing mothers' parenting strain and providing solutions, it is imperative to extensively consider what family needs are and what solutions are required to resolve those needs.