Nonstationary vapor concentration fields near the droplet of binary solution growing in the vapor-gas mixture are revealed using the concepts of similarity. The revealed fields are determined with the exact account of the motion of droplet surface and refer to the times at which the droplet reaches sizes that provide for the diffusion regime of droplet growth. To obtain the self-similar solution of the problem of binary condensation, it is necessary to ensure a constant (in time) concentration of binary solution in the growing droplet. The velocities of an increase in the number of molecules and the radius of two-component droplet with time are found with allowance for the equation ensuring this solution. The conditions for the transformation of the self-similar solution of the problem of the condensation of two-component mixture into the solution, which was derived previously for the condensation of one component, are elucidated.