With the rapid penetration of smartphones, sharing economy platforms have become popular. Especially, car-sharing, is widely spread in the world and its market size is growing. Nevertheless, there is still controversy over the safety and security issues in the car-sharing platform. This paper proposes one of possible threats by car-sharing platforms, an increasing car crash rates of teenage drivers. Teenagers are more susceptible to newly adopted digital platforms. Teenage drivers are more likely to be in a car crash than adult drivers. With the entry of car-sharing platforms, it has become easier for teenagers to access cars than before. We assume that the increased number of teenage drivers through car-sharing is related to the increase of car crashes of teenage drivers. To identify this, we employ differences-in-differences (DID) approach with the data set of car crashes in 224 counties and find that the entry of car-sharing significantly increases car crashes of teenage drivers.