A steam turbine plant, comprising: a steam turbine (2, 3); and a condenser; the condenser comprising: a set of heat-transfer tubes which is configured of a plurality of heat-transfer tubes through the inner portions of which a medium which performs heat-exchange with exhaust steam exhausted from a steam turbine passes and which turns the exhaust steam back into water; a main body which covers the set of heat-transfer tubes; an intermediate body which is positioned between the steam turbine and the main body and connects both, and forms a primary steam passage for guiding the exhaust steam from the steam turbine to the set of heat-transfer tubes in the main body; and a bypass steam receiving section which receives bypass steam which has bypassed the steam turbine, and guides the bypass steam to the set of heat-transfer tubes in the main body via an opening formed in the main body, characterized in that the opening of the main body is formed at a position at which the bypass steam mainly flows into the set of heat-transfer tubes from a region different from an inflow region through which the exhaust steam mainly flows into the set of heat-transfer tubes via the primary steam passage; wherein the steam turbine is a horizontal exhaust type which exhausts steam in an axial direction in which a rotor of the steam turbine extends, or to a side of the steam turbine, wherein the intermediate body is connected to a side portion of the main body, and wherein the bypass steam receiving section is disposed outside the primary steam passage, and is provided on an upper portion of the main body. a steam turbine (2, 3); and a condenser; the condenser comprising: a set of heat-transfer tubes which is configured of a plurality of heat-transfer tubes through the inner portions of which a medium which performs heat-exchange with exhaust steam exhausted from a steam turbine passes and which turns the exhaust steam back into water; a main body which covers the set of heat-transfer tubes; an intermediate body which is positioned between the steam turbine and the main body and connects both, and forms a primary steam passage for guiding the exhaust steam from the steam turbine to the set of heat-transfer tubes in the main body; and a bypass steam receiving section which receives bypass steam which has bypassed the steam turbine, and guides the bypass steam to the set of heat-transfer tubes in the main body via an opening formed in the main body, characterized in that the opening of the main body is formed at a position at which the bypass steam mainly flows into the set of heat-transfer tubes from a region different from an inflow region through which the exhaust steam mainly flows into the set of heat-transfer tubes via the primary steam passage; wherein the steam turbine is a horizontal exhaust type which exhausts steam in an axial direction in which a rotor of the steam turbine extends, or to a side of the steam turbine, wherein the intermediate body is connected to a side portion of the main body, and wherein the bypass steam receiving section is disposed outside the primary steam passage, and is provided on an upper portion of the main body. a set of heat-transfer tubes which is configured of a plurality of heat-transfer tubes through the inner portions of which a medium which performs heat-exchange with exhaust steam exhausted from a steam turbine passes and which turns the exhaust steam back into water; a main body which covers the set of heat-transfer tubes; an intermediate body which is positioned between the steam turbine and the main body and connects both, and forms a primary steam passage for guiding the exhaust steam from the steam turbine to the set of heat-transfer tubes in the main body; and a bypass steam receiving section which receives bypass steam which has bypassed the steam turbine, and guides the bypass steam to the set of heat-transfer tubes in the main body via an opening formed in the main body, characterized in that the opening of the main body is formed at a position at which the bypass steam mainly flows into the set of heat-transfer tubes from a region different from an inflow region through which the exhaust steam mainly flows into the set of heat-transfer tubes via the primary steam passage; wherein the steam turbine is a horizontal exhaust type which exhausts steam in an axial direction in which a rotor of the steam turbine extends, or to a side of the steam turbine, wherein the intermediate body is connected to a side portion of the main body, and wherein the bypass steam receiving section is disposed outside the primary steam passage, and is provided on an upper portion of the main body.