| Masanori Hayashi | |
| Position: | Pitcher |
| Bats: | Left |
| Throws: | Left |
| Birth Date: | 19 September 1983 |
| Birth Place: | Funabashi, Chiba, Japan |
| Debutleague: | NPB |
| Debutdate: | June 28 |
| Debutyear: | 2003 |
| Debutteam: | Yomiuri Giants |
| Finalleague: | NPB |
| Finaldate: | July 21 |
| Finalyear: | 2015 |
| Finalteam: | Yokohama DeNA BayStars |
| Stat1label: | Win–loss record |
| Stat1value: | 22–26 |
| Stat2label: | Earned run average |
| Stat2value: | 3.49 |
| Stat3label: | Strikeouts |
| Stat3value: | 502 |
| Teams: | |
is a former professional Japanese baseball player. He played as a pitcher in Nippon Professional Baseball (NPB) for the Yomiuri Giants (2002–2008), the Hokkaido Nippon-Ham Fighters (2009–2011) and the Yokohama DeNA BayStars (2012–2017).