To safely start and operate electrical devices accommodated in a local electrical room located in a hazardous area, a plant module (2) includes: a group of plant equipment (6) that constitutes a plant; a local electrical room (5) located in a hazardous area (31) defined by presence of combustible gas and accommodating a power device configured to supply electric power to the group of plant equipment (6); a structure (21) supporting the group of plant equipment (6) and the local electrical room (5); and an outside air supply device (64) having explosion-proof properties and arranged at the local electrical room (5) to supply outside air to an inside thereof, wherein the plant module (2) is configured to supply the electric power to the outside air supply device (64) from a non-hazardous area.