The expression for the determination of the magnetic activity period for lower main-sequence stars is derived from the analysis of drift of magnetic structures with the solar cycle activity. The expression linked the activity period of a star with its rotation period T_rot, B-V color index and average level of chromospheric emission ⟨R'_HK⟩. The activity periods for 30 stars (14 young and 16 old stars) from the Wilson sample are calculated. The calculated and observed activity periods are in good agreement.