Adopting the theory of enter-educate, this study was conducted to prevent the smoking by middle school students who had not started smoking yet. A famous pop music singer with high popularity among teenagers was cast on the public sponsored advertisement (PSA) on smoking prevention. This PSA was televised through major TV stations for two months. The effectiveness of this project was evaluated seven times. The effectiveness of the PSA, the role of the cast singer, the rate of seeing the PSA, and the impression about the PSA were evaluated. The viewer survey since the second period of the PSA revealed that most of the middle school students (79~94 percent) watched it. Among TV stations, MBC recorded the highest viewer rate as 69.6~72.0 percent of the middle school students watched the PSA at least once from this station. Also, the viewer rates of such cable TV stations as Mnet and OCN were quite high for their advertisement prices. The overall impression about the PSA was favorable. The contribution of the singer to this positive outcome was 60 percent and over. The effect of smoking prevention was also high as 93.7 percent of the middle school students replied that they would not start smoking. However, since this study dealt with the general public, it was not possible to control the effect of other factors systematically. Also, we could not measure the differences bewteen the pre-PSA and the post-PSA periods, so that the interpretation of the results has some limitation.