We present the results of age determination for galactic B-type main sequence stars which are components of double-lined eclipsing binaries. Only detached systems are considered. We analyze 38 binary systems that meet such criteria. The analysis is based on evolutionary computations and we consider that the age is determined if there is a common value from the radius−age diagrams and the agreement in the position of both components in the Hertzsprung-Russell diagram. In some cases, to meet these two conditions, it was necessary to adjust the value of the metallicity, Z or/and the parameter of overshooting from the convective core, αov. We determine the consistent age for 33 binaries out of 38. Besides, we made an extensive computations and for each system we give the range of αov and Z, for which the consistent solutions exist. The age of the studied B-type main sequence stars ranges, as counted from the Zero Age Main Sequence, from about 2.5 Myr to about 200 Myr.