Good mental health of caregivers is crucial for maintaining strong relationships between caregivers and care-recipients, which in turn is important for positive caregiving outcomes. We have developed a structured floral arrangement (SFA) program for neurocognitive disorders to improve visuospatial memory, whereby patients are asked to arrange real flowers and leaves according to an instruction sheet, and then take the arrangements back home to enjoy with their caregivers (family members or care staff ). Previous studies with the SFA program revealed that it improves the visuospatial memory of treated patients and the production of the arrangements encouraged them to continue the cognitive training. However, the impact of the arrangements on mental health of the caregivers at home has been unclear. We therefore investigated the effects of these floral arrangements on primary caregivers' mental health. Our results showed that the mean total GHQ-28 score of caregivers improved significantly when spending time with the arrangements (P<0.05), although no changes were found in control caregivers who were not exposed to arrangements in the home. Mean scores of the GHQ-28 Anxiety and Insomnia sub-category was significantly improved in caregivers exposed to the arrangements. These results suggest that caregivers are affected positively by arrangements of real flowers and leaves made by their care-recipients. The SFA program could therefore contribute to improving the mental health of caregivers as well as the visuospatial memory of patients with neurocognitive disorders.