We report two cases of Stickler syndrome type 1 accompanied by a membranous vitreous anomaly in two Japanese sisters. A nine-year-old girl was referred to us for a rhegmatogeneous retinal detachment in her right eye. She had moderate myopia and a membranous vitreous anomaly in both eyes. She also had micrognathia and a saddle nose, leading to a diagnosis of Stickler syndrome type 1. The retinal detachment persisted even after scleral buckling surgery; however, the retina was reattached after 25-gauge microincision vitreous surgery 11 days later. Her seven-year-old sister had been diagnosed with Pierre Robin sequence due to micrognathia, cleft palate, and saddle nose. She was myopic by about -9.0 diopters with a membranous vitreous anomaly in both eyes and circumferential perivascular retinal degeneration in the right eye. Genetic analyses showed that both sisters and their mother carried the same mutation in the COL2A1 gene. The findings in these sisters indicate that retinal detachment is associated with Stickler syndrome type 1. Micro-incison vitreous surgery might be effective for rhegmatogeneous retinal detachment with high vitreous liquefaction.