C小调是一个于C音开始的音乐的小调，组成的音有C、D、降E、F、G、降A、降B及C（和声小调）。C小调是一个有三个降号的调。

它的相对大调是降E大调，并行大调是C大调。

C minor (abbreviated c or Cm) is a minor scale based on C, consisting of the pitches C, D, E♭, F, G, A♭, and B♭. The harmonic minor raises the B♭ to B♮. Changes needed for the melodic and harmonic versions of the scale are written in with naturals and accidentals as necessary.