小七和弦（Minor Seventh Chord），在 音乐理论上是一组由 根音、小三度、纯五度和 小七度构成的和弦。也可以被看作是一个小三和弦(或曰「小调三和弦」)附加一个小七度音。在流行音乐的标记符号体系中，其标示方法是：在一个标示和弦根音的字母之后，上标「m7」 或 「-7」，以图标C和弦为例则表示方法为: Cm7、C-7…等。以数字表示Cm7组成音则为「1 、b3、 5、b7」。

In music, a minor seventh chord is any nondominant seventh chord where the "third" note is a minor third above the root.

Most typically, minor seventh chord refers to where the "seventh" note is a minor seventh above the root (a fifth above the third note). This is more precisely known as a minor/minor seventh chord, and it can be represented as either as m7 or -7, or in integer notation, {0, 3, 7, 10}. In a natural minor scale, this chord is on the tonic, subdominant, and dominant degrees. In a harmonic minor scale, this chord is on the subdominant degrees. In an ascending melodic minor scale, this chord is on the supertonic degree. In a major scale, this chord is on the second (supertonic seventh), third (mediant) or sixth (submediant) degrees. For instance the ii in the ii-V-I turnaround.