A transformer device comprising: a transformer including a first phase transformer, a second phase transformer stacked above the first phase transformer, and a third phase transformer stacked above the second phase transformer, each phase transformer including a core and a coil wound around the core; a suspension tool attachment unit disposed above the coil and connected to the core of the third phase transformer, and a cover body having an internal space that accommodates the transformer and connected to the suspension tool attachment unit, wherein a suspension tool for suspending the transformer device including the transformer and the cover body is attachable to the suspension tool attachment unit, the transformer device further comprises: a first connection member that connects the core of the first phase transformer and the core of the second phase transformer; a second connection member that connects the core of the second phase transformer and the core of the third phase transformer; and a lower frame disposed below the first phase transformer and connected to the first phase transformer, the cover body is supported by the suspension tool attachment unit and the lower frame, the cover body is provided with: a first opening located below the first phase transformer and allowing communication between the internal space and a space outside the internal space; and a second opening located above the third phase transformer and allowing communication between the internal space and the space outside the internal space, and an air flow is formed such that air flows into the internal space through the first opening and is discharged to the space outside the internal space through the second opening. a transformer including a first phase transformer, a second phase transformer stacked above the first phase transformer, and a third phase transformer stacked above the second phase transformer, each phase transformer including a core and a coil wound around the core; a suspension tool attachment unit disposed above the coil and connected to the core of the third phase transformer, and a cover body having an internal space that accommodates the transformer and connected to the suspension tool attachment unit, wherein a suspension tool for suspending the transformer device including the transformer and the cover body is attachable to the suspension tool attachment unit, the transformer device further comprises: a first connection member that connects the core of the first phase transformer and the core of the second phase transformer; a second connection member that connects the core of the second phase transformer and the core of the third phase transformer; and a lower frame disposed below the first phase transformer and connected to the first phase transformer, the cover body is supported by the suspension tool attachment unit and the lower frame, the cover body is provided with: a first opening located below the first phase transformer and allowing communication between the internal space and a space outside the internal space; and a second opening located above the third phase transformer and allowing communication between the internal space and the space outside the internal space, and an air flow is formed such that air flows into the internal space through the first opening and is discharged to the space outside the internal space through the second opening. a first connection member that connects the core of the first phase transformer and the core of the second phase transformer; a second connection member that connects the core of the second phase transformer and the core of the third phase transformer; and a lower frame disposed below the first phase transformer and connected to the first phase transformer, the cover body is supported by the suspension tool attachment unit and the lower frame, the cover body is provided with: a first opening located below the first phase transformer and allowing communication between the internal space and a space outside the internal space; and a second opening located above the third phase transformer and allowing communication between the internal space and the space outside the internal space, and a first opening located below the first phase transformer and allowing communication between the internal space and a space outside the internal space; and a second opening located above the third phase transformer and allowing communication between the internal space and the space outside the internal space, and an air flow is formed such that air flows into the internal space through the first opening and is discharged to the space outside the internal space through the second opening.