Background: Human sapovirus (SaV) causes sporadic and endemic acute gastroenteritis worldwide. However, little is known about the relationship between the mode of transmission and genetic characteristics of SaV. Objective: To investigate the molecular characteristics of SaV-associated acute gastroenteritis among sporadic cases, foodborne, and nonfoodborne outbreaks. Study design: We performed a systematic review of publications and genetic analysis of SaV in fecal specimens from 98 outpatients with acute gastroenteritis, 32 stool samples from 8 foodborne outbreaks, and 63 stool samples from 23 nonfoodborne outbreaks in Miyagi Prefecture, Japan from 1993 and between 2004 and 2020. Reverse transcription polymerase chain reaction (RT-PCR) was employed for the detection of SaV, and the partial capsid gene was sequenced for genotyping and phylogenetic analysis. Results: The overall detection rate of SaV in sporadic cases, foodborne, and nonfoodborne outbreaks was 5.8, 1.7, and 4.3%, respectively. Genotypic analysis revealed GI.1 to be the predominant genotype in sporadic cases (31.5%) and nonfoodborne outbreaks (52.1%), whereas it was not detected in foodborne outbreaks. Some outbreaks occurred following sporadic cases with the same genotype. Conclusions: The distribution of SaV genotypes was different between foodborne outbreaks and other settings. The effective SaV infection control may differ depending on the genomic characteristics.