Individuals with depression experience more negative imagery and less vivid positive imagery, and the late positive potential (LPP) is considered as a viable biomarker for negative attentional and memory biases in depression; however, the LPP response to emotional imagery in depressed individuals remains unclear. This study aims to investigate neural response to emotional imagery in depressed individuals. ERPs were recorded from 40 depressed participants and 44 healthy controls during the encoding-imagery task. Depressed participants scored significantly lower in the valence rating of sad and neutral imagery compared to healthy participants. Importantly, the LPP amplitudes to sad imagery in depressed participants were significantly larger than healthy controls, particularly in the middle (800-1,400 ms) and late time windows(1,400-2,000 ms). Furthermore, depressed individuals exhibited significantly higher LPP amplitudes for sad imagery compared to happy imagery, whereas healthy participants showed the opposite pattern. The present study provides evidence that depressed individuals display abnormal electrophysiological reactivity to sad imagery, which offers a new perspective for understanding the mechanisms underlying depression.