升音符（Sharp）是在乐谱中，放在音符前面的符号，代表这个音符的音高要比实际标定的高半音，读作“升某音”。

在十二平均律理论，升B等于正常的C音，升G等于降A。但在经典音乐理论中，升半音和降半音是由五度音高推演出来的，两个音之间尚有微小的差别。

此外还有“倍升音符”，用表示升两个半音，也就是一个音高。此外还有升三个半音高的，用两个符号迭加表示，但应用的很罕见。

此外还有升1/2个半音，即1/4个音高，用多种符号表示，有用半个升音符表示的。

In music, sharp, dièse (from French), or diesis (from Greek) means higher in pitch. More specifically, in musical notation, sharp means "higher in pitch by a semitone (half step)," and has an associated sharp symbol, ♯, which may be found in key signatures or as an accidental. Sharp is contrasted with flat, which refers to a lowering of pitch. Intonation may be flat, sharp, or both, successively or simultaneously.