A spectral probe for blood vessel diagnosis that can be used for diagnosing blood vessels with high reliability, without imposing an excessive burden on patients. Typical examples of such videos are a home video taken by a digital camera and a segment, or clip, of a professional video or film. Using a control program stored on the device, the device interactively establishes an in-circuit programming exchange with a remote partner, and updates data and software, including the in-circuit programming instruction set, when needed. The measuring unit is fixed to the casing and connected to an external pipe with a measuring unit protecting joint interposed therebetween.