Studies of the magnetic fields of Herbig Ae/Be (HAeBe) stars can aid in understanding how the magnetic fields of AB stars of intermediate mass are created and evolve. It has been shown that the magnetic fields and magnetic fluxes of HAeBe stars before they emerge on the main sequence are significantly lower than for their successors, main sequence AB stars. In order to explain this mystery, the effect of accretion on Herbig stars and their magnetic fields is studied. Evidence is found in favor of the assumption that in magnetic HAeBe stars with a higher rate of accretion the magnetic fields are lower on the average. However, since the accretion rates fall off exponentially with the age of a star, even if it should be confirmed, this effect cannot fully explain the discontinuous increase in the magnetic fields and magnetic fluxes when HAeBe stars enter the main sequence.