This study was conducted to apply a horticultural therapy program to childhood cancer patients, to analyze their psychosocial changes and thus to examine its possibility as a way to manage the recovery of childhood cancer patients. This study was conducted on patients who were diagnosed with childhood cancer, and they were divided into the experimental group (8 patients who visited H association offices located in 3 cities and participated in the horticultural program) and the control group (5 patients who did not participate in the program). The homogeneity between the two groups before conducting the program was compared, and there was no statistically significant difference, which proved that the two groups were homogeneous. After conducting the program, the score of social immaturity, one of the sub-categories of problem behaviors, of the experimental group was statistically significantly lower than that of the control group (p=.019). Changes before and after the program within the groups were compared, and the somatization score (p=.039) of the experimental group (p=.039) after the program was 1.13, down from 2.13 before the program. The social immaturity score (p=.017) of the experimental group after the program was 1.00, down from 2.63 before the program, and the attention problem score (p=.026) of the group after the program was 1.25, down from 2.50 before the program. The total problem behavior score (p=.034) of the experimental group after the program was 9.63, down from 18.50 before the program, showing a statistically significant decrease. The cumulative subjective mood score (p=.000) of the experimental group throughout the entire sessions after the program was 7.82, up from 6.99 before the program, showing a statistically significant increase. Therefore, it can be concluded that the horticultural therapy program developed based on the ‘relaxationsocial support-cognitive behavior’ strategy was effective to reduce the negative psychosocial state of childhood cancer patients.