A work machine comprising: a work device including a plurality of work members (2, 4, 6); a single rod-type hydraulic cylinder that drives one of the plurality of work members (2, 4, 6); a bottom-side line connected to a bottom chamber of the single rod-type hydraulic cylinder; a rod-side line connected to a rod chamber of the single rod-type hydraulic cylinder; a bidirectional-type first hydraulic pump of which a delivery port on one side is connected to the bottom-side line through a first control valve and a delivery port on another side is connected to the rod-side line through the first control valve; a bidirectional-type second hydraulic pump of which a delivery port on one side is connected to the bottom-side line through a second control valve and a delivery port on another side is connected to the rod-side line through the second control valve; an operation lever device having an operation lever for operating the single rod-type hydraulic cylinder to extend and contract; a working fluid tank; a flushing valve that is connected to the bottom-side line and the rod-side line, and that discharges a surplus flow rate of a lower-pressure side one of the bottom-side line and the rod-side line into the working fluid tank when a differential pressure between the bottom-side line and the rod-side line exceeds a predetermined pressure; and a controller that controls opening/closing of the first control valve and the second control valve and controls tilting amounts of the first hydraulic pump and the second hydraulic pump, characterized in that the work machine further includes a bottom pressure sensor that detects a pressure in the bottom chamber; a rod pressure sensor that detects a pressure in the rod chamber; a rod-side discharge line (205, 207, 209) that connects the rod-side line and the working fluid tank; and a rod-side proportional valve provided in the rod-side discharge line (205, 207, 209), and the controller is configured to, when the operation lever is operated to a side of extending the single rod-type hydraulic cylinder in a state in which the pressure in the rod chamber is higher than the pressure in the bottom chamber, open the rod-side proportional valve to discharge a working fluid in the rod chamber into the working fluid tank such that a differential pressure between the pressure in the rod chamber and the pressure in the bottom chamber is reduced below the predetermined pressure. a work device including a plurality of work members (2, 4, 6); a single rod-type hydraulic cylinder that drives one of the plurality of work members (2, 4, 6); a bottom-side line connected to a bottom chamber of the single rod-type hydraulic cylinder; a rod-side line connected to a rod chamber of the single rod-type hydraulic cylinder; a bidirectional-type first hydraulic pump of which a delivery port on one side is connected to the bottom-side line through a first control valve and a delivery port on another side is connected to the rod-side line through the first control valve; a bidirectional-type second hydraulic pump of which a delivery port on one side is connected to the bottom-side line through a second control valve and a delivery port on another side is connected to the rod-side line through the second control valve; an operation lever device having an operation lever for operating the single rod-type hydraulic cylinder to extend and contract; a working fluid tank; a flushing valve that is connected to the bottom-side line and the rod-side line, and that discharges a surplus flow rate of a lower-pressure side one of the bottom-side line and the rod-side line into the working fluid tank when a differential pressure between the bottom-side line and the rod-side line exceeds a predetermined pressure; and a controller that controls opening/closing of the first control valve and the second control valve and controls tilting amounts of the first hydraulic pump and the second hydraulic pump, characterized in that the work machine further includes a bottom pressure sensor that detects a pressure in the bottom chamber; a rod pressure sensor that detects a pressure in the rod chamber; a rod-side discharge line (205, 207, 209) that connects the rod-side line and the working fluid tank; and a rod-side proportional valve provided in the rod-side discharge line (205, 207, 209), and a bottom pressure sensor that detects a pressure in the bottom chamber; a rod pressure sensor that detects a pressure in the rod chamber; a rod-side discharge line (205, 207, 209) that connects the rod-side line and the working fluid tank; and a rod-side proportional valve provided in the rod-side discharge line (205, 207, 209), and the controller is configured to, when the operation lever is operated to a side of extending the single rod-type hydraulic cylinder in a state in which the pressure in the rod chamber is higher than the pressure in the bottom chamber, open the rod-side proportional valve to discharge a working fluid in the rod chamber into the working fluid tank such that a differential pressure between the pressure in the rod chamber and the pressure in the bottom chamber is reduced below the predetermined pressure.