Using published data and new data from mm observations, we calculate spectral indices α(12μ-25μ), α(25μ-1.1mm) and α(1.1mm-2cm) for Be stars. The index α(25μ-1.1mm), obtained for 8 stars, shows two characteristics: 1) for “normal” Be stars the index decreases from earlier types towards later types, i.e., later type Be stars tend to have shallower spectra in the IR-radio region than earlier types; 2) the index for shell stars appears to have smaller values than that for normal Be stars with same spectral types.