Nurses are at the forefront in fighting against Covid-19 and are most likely in face-to-face interactions with patients in clinics or hospitals. Their jobs put them at risk of being infected by a coronavirus, forced them to wear protective equipment which made them uncomfortable, demanded them to deal with uncertainties, and handled patients who mostly fear of being infected by the virus when they visited a hospital. Having a belief that one can master certain situations and overcome obstacles is so-called self-efficacy. It is hard for nurses to carry out their roles during the Covid-19 pandemic, but social support may help to reduce stress and psychological burden. The study aims to examine the effect of family support on nurses' self-efficacy during the Covid-19 pandemic. Participants consisted of 98 nurses who worked in a private hospital in the Central Java province. We used the following scales to collect data: the Family Support Scale and the Self-efficacy Scale distributed to the participants using online and offline modes. The results of simple regression analysis showed an effect of family support on nurses' self-efficacy during the Covid-19 pandemic (p-value<0.001). Family support contributed 50.6% to nurse efficacy. Further studies may investigate other factors influencing nurses' efficacy during the Covid-19 pandemic.