Provided are a signal processing apparatus, a signal processing method, and an imaging apparatus for estimating depth with a high degree of accuracy from video signals of a plurality of cameras. The signal processing apparatus includes a detection unit that detects depth from video captured by a plurality of cameras, an estimation unit that estimates camera motion by detecting a camera position, a prediction unit that predicts present depth from camera motion and depth obtained previously, and a synthesis unit that synthesizes depth detected by the detection unit and depth predicted by the prediction unit on the basis of a result of estimating the amount of blur that occurs in each image captured by cameras. The amount of blur can be estimated using camera motion, previous depth information, and shutter time.