His strongest influence seems to have been Giorgio de Chirico, and therefore his works have been variously classed as Magic Realism, Metaphysical Art or Surrealism ... the terms can overlap.
As can be seen below, Delvaux usually included women, often unclothed, in his paintings. Men, if they appeared, were normally fully dressed. Settings were often at dusk or night, usually in towns or cities. Generally his subjects are static, no action shown and little implied. People and other subjects are slightly simplified and distorted. In sum, what the viewer sees is clearly not quite real.