A description of the Gibbs energy of the various solid modifications of manganese at 101325 Pa has been obtained for the whole temperature range from 298 K to the melting point. The present analysis accounts for the effect of a magnetic transition in α-, γ-, and δ-Mn, which is treated using the Inden-Hillert-Jarl phenomenological model for the magnetic Gibbs energy. Our description involves smaller magnetic contributions to the entropy of these phases than suggested in the classical work by Weiss and Tauer. An expression for the Gibbs energy of the liquid phase is also reported.