  We have measured a response to a black body radiation and noise of the
cold-electron bolometers. The experimental results have been fitted by
theoretical model with two heat-balance equations. The measured noise has been
decomposed into several terms with the help of theory. It is demonstrated that
the photon noise exceeds any other noise components, that allows us to conclude
that the bolometers see the photon noise. Moreover, a peculiar shape of the
noise dependence on the absorbed power originates completely from the photonic
component according to the theory. In the additional experiment on heating of
the cryostat plate together with the sample holder we have observed nearly
independence of the noise on the electron temperature of the absorber, which
has provided another proof of the presence of the photon noise in the first
experiment.
