Norovirus is a leading cause of acute non-bacterial gastroenteritis worldwide, affecting developing and developed countries, both children and adults. This study describes an outbreak of acute gastroenteritis at a daycare center of a tertiary level hospital in Bangkok, Thailand during October 2014. Although none of the staff became symptomatic, 8 of 11 children attending the center and 4 of their household contacts developed acute gastroenteritis. No pathogenic bacteria or rotavirus were detected in their evaluation; however, 3 out of 7 stool samples from the cases were positive for norovirus GII.17. Reverse transcriptase polymerase chain reaction analysis with sequence and phylogenetic analysis revealed the viral strain was the same strain reported from Taiwan in 2013. Because norovirus is a frequent cause of outbreaks in crowded conditions, early detection and preventive measures are important to control outbreaks.