We have analyzed magnetic field measurements and evaluated the distribution of rms magnetic fields B (in G) and magnetic fluxes F (in G cm2) for 23 Herbig Ae/Be stars. The distributions of B and F values can be fitted by log-normal distributions with the mean values overline{log B} = 2.2, overline{log Φ} = 25.7 and widths σ(overline{log B}) = 0.3, σ(overline{log Φ} = 0.5. The obtained distribution widths appear to be almost the same as for the main sequence (MS) AB stars, while the mean values seem to be significantly smaller than those for MS AB stars (2.5 and 26.4 respectively). The causes of these differences and possible scenarios of magnetic field evolution in intermediate-mass stars before the MS are discussed.