Aiming at solving a social challenge for compatibility of infection risk mitigation with better QOL to prevent viral contact infection via hands, an effect of ethanol (EtOH) combined with benzalkonium chloride (BC) on inactivation of Influenza virus A (IVA) and SARS-CoV-2 was investigated under conditions of exposure time, 30 sec. Although either just 20–30 vol% EtOH or just 0.05w/v% BC were weak for the inactivation, the combination showed the synergic effects. It was also demonstrated that a commercial hand sanitizer containing both 44 vol% EtOH and 0.05w/v% BC is effective to highly inactivate IVA and SARS-CoV-2. The consideration on the practical usage of hand sanitizers suggests that 20–50 vol% EtOH combined with 0.05 w/v% BC would be effective and beneficial. The COVID-19 pandemic has revealed the emerging importance of community infection control which is different from a long-term challenge on hospital infection management, and a new hand sanitizing-system using lower EtOH combined with BC is expected to be a measure of community infection control.