To provide an eccentricity detection method for an inner tube of a concentrate burner that quickly detects eccentricity of an inner tube of a concentrate burner causing a worse flash smelting furnace status and prompts a corresponding correction, and also to provide a detection device that suitably executes the method.

An outer tube 12 in an inner/outer double tube structure part of the concentrate burner 9 has inner tube observation holes 14 in a plurality of places. Through the inner tube observation holes, laser range finders 15 measure distances to the inner tube 11, and according to the results, eccentricity of the inner tube of the concentrate burner is detected. Each inner tube observation hole and the laser range finder corresponding to the hole are coupled with a range finding laser guide tube 16.