To the problem of physical constant dependence on time

Evaluation of the upper limit of a hypothetic change of electron and proton mass ratio μ=me/mp at the cosmological time scale is obtained from the analysis of wavelengths of the lines of molecular hydrogen observed in the PKS 0528-250 quasar spectrum. It is shown that the upper limit of μ change rate is μ/μ ≤ 3x10-13 years-1. This is by two orders lower than the value of μ/μ=(2.3±0.3)x10-11 years-1 corresponding to the results of laboratory measurements