We introduced the medication support and adverse events monitoring system using medical social networking service (SNS).Thirty-two gastric cancer patients who were treated with oral anticancer drugs were included in this study. Patients or their families input the status of medication and adverse events using the ICT terminal every day, and the pharmacist confirmed the input contents on the PC. If there was a serious adverse events, the nurse confirmed the status of patient by telephone.Of the 32 registered cases, 3 cases (9.3%) discontinued input within less than 2 months during treatment. We experienced a case whose adverse events could be dealt with during long vacations and a case whose treatment could be continued by sharing information with home-visit nursing stations. In the questionnaire survey, there were many opinions that it would lead to anxiety reduction.Medication support system using medical SNS can be a safe and useful tool.