A sludge dewatering system, comprising: a concentration apparatus (12; 12a) that concentrates sludge while conveying the sludge on a top surface of a filter body; and a dewatering apparatus that subjects the sludge discharged from the concentration apparatus (12; 12a) to pressure dewatering, wherein the concentration apparatus (12; 12a) includes: a first chemical feeder that is configured to add a first chemical agent to sludge, a filter cloth belt, which is provided as filter body, that is configured to subject the sludge to which the first chemical agent is added to gravity filtration while conveying the sludge on a top surface to a conveyance direction, a second chemical feeder in which an addition nozzle is provided above the filter cloth belt, the second chemical feeder is configured to add a second chemical agent to sludge on the filter cloth belt from the addition nozzle, a movement mechanism that includes a screw (40a, 40b) which is provided on the filter cloth belt at a downstream side of the second chemical feeder, the screw (40a, 40b) extending in a direction intersecting with the conveyance direction, and moving sludge to an extending direction of the screw (40a, 40b) by rotation thereof. a concentration apparatus (12; 12a) that concentrates sludge while conveying the sludge on a top surface of a filter body; and a dewatering apparatus that subjects the sludge discharged from the concentration apparatus (12; 12a) to pressure dewatering, wherein the concentration apparatus (12; 12a) includes: a first chemical feeder that is configured to add a first chemical agent to sludge, a filter cloth belt, which is provided as filter body, that is configured to subject the sludge to which the first chemical agent is added to gravity filtration while conveying the sludge on a top surface to a conveyance direction, a second chemical feeder in which an addition nozzle is provided above the filter cloth belt, the second chemical feeder is configured to add a second chemical agent to sludge on the filter cloth belt from the addition nozzle, a movement mechanism that includes a screw (40a, 40b) which is provided on the filter cloth belt at a downstream side of the second chemical feeder, the screw (40a, 40b) extending in a direction intersecting with the conveyance direction, and moving sludge to an extending direction of the screw (40a, 40b) by rotation thereof. a first chemical feeder that is configured to add a first chemical agent to sludge, a filter cloth belt, which is provided as filter body, that is configured to subject the sludge to which the first chemical agent is added to gravity filtration while conveying the sludge on a top surface to a conveyance direction, a second chemical feeder in which an addition nozzle is provided above the filter cloth belt, the second chemical feeder is configured to add a second chemical agent to sludge on the filter cloth belt from the addition nozzle, a movement mechanism that includes a screw (40a, 40b) which is provided on the filter cloth belt at a downstream side of the second chemical feeder, the screw (40a, 40b) extending in a direction intersecting with the conveyance direction, and moving sludge to an extending direction of the screw (40a, 40b) by rotation thereof.