Kostromskaja eparhija) is an eparchy of the Russian Orthodox Church in Russia.

On July 16, 1744, Empress Elizabeth Petrovna signed a decree establishing the four noble cities at the Kostroma episcopal.

As a member of the Holy Synod, it was necessary for him to stay in the capital as he awaited transfer on August 18, 1745, to the Department of Pskov.

According to the Synod's Report of June 18, 1744, the provinces of Kostroma and Galich had 786 churches, 27 monasteries and 8 nunneries.

With the transfer of Bishop Simon to Kostroma, Archimandrite Sylvester (Kulyabko) was appointed as the rector of the Kiev Theological Academy and consecrated Bishop of Kostroma and Galich in St. Petersburg on November 10, 1745.