To provide marine engine steam turbine equipment which can immediately stop rotation of a propeller connected via a speed reducer, during turbine trip, which can promptly rotate the propeller in both backward and forward directions during auto spinning, and which can rotate the propeller in the forward direction when an HP turbine and an LP turbine have no failure even if an IP turbine fails.

A bypass steam pipe 51 which directly guides reheated steam heated by a reheater 25 to a main steam condenser 37, is formed by branching off in the middle of a reheated steam pipe 34 which guides the steam heated by the reheater 25 to a low-pressure-side turbine 22. A reheated steam dump valve 52 is provided in the middle of the bypass steam pipe 51.