A work vehicle comprising: a plurality of wheels provided on a vehicle body; a work device provided on a front portion of the vehicle body to perform operations of moving and loading load materials; a brake device (41F, 41R) configured to apply a brake force to the plurality of wheels; a brake pedal for operating the brake device; a brake valve configured to control a brake pressure to be output to the brake device based on a step-on amount of the brake pedal; a solenoid proportional valve configured to output a pilot pressure to the brake valve; and a controller configured to control the solenoid proportional valve, wherein the work vehicle further comprises: a step-on amount sensor configured to detect the step-on amount of the brake pedal; a vehicle speed sensor configured to detect a vehicle speed; and a load sensor configured to detect a weight of the load materials loaded in the work device, the controller stores a plurality of control characteristics each of which is set such that a control pressure of the solenoid proportional valve increases as the step-on amount of the brake pedal increases, and in a case where the step-on amount is equal to or less than a predetermined step-on amount, an increase rate of the control pressure of the solenoid proportional valve with respect to the step-on amount of the brake pedal varies, and the controller is further configured to: in a case where the step-on amount detected by the step-on amount sensor is equal to or less than the predetermined step-on amount, select one control characteristic from among the plurality of control characteristics based on at least one of the vehicle speed detected by the vehicle speed sensor and the weight detected by the load sensor; calculate the control pressure corresponding to the step-on amount detected by the step-on amount sensor based on the selected one control characteristic; and output a command current value according to the calculated control pressure to the solenoid proportional valve. a plurality of wheels provided on a vehicle body; a work device provided on a front portion of the vehicle body to perform operations of moving and loading load materials; a brake device (41F, 41R) configured to apply a brake force to the plurality of wheels; a brake pedal for operating the brake device; a brake valve configured to control a brake pressure to be output to the brake device based on a step-on amount of the brake pedal; a solenoid proportional valve configured to output a pilot pressure to the brake valve; and a controller configured to control the solenoid proportional valve, wherein the work vehicle further comprises: a step-on amount sensor configured to detect the step-on amount of the brake pedal; a vehicle speed sensor configured to detect a vehicle speed; and a load sensor configured to detect a weight of the load materials loaded in the work device, a step-on amount sensor configured to detect the step-on amount of the brake pedal; a vehicle speed sensor configured to detect a vehicle speed; and a load sensor configured to detect a weight of the load materials loaded in the work device, the controller stores a plurality of control characteristics each of which is set such that a control pressure of the solenoid proportional valve increases as the step-on amount of the brake pedal increases, and in a case where the step-on amount is equal to or less than a predetermined step-on amount, an increase rate of the control pressure of the solenoid proportional valve with respect to the step-on amount of the brake pedal varies, and the controller is further configured to: in a case where the step-on amount detected by the step-on amount sensor is equal to or less than the predetermined step-on amount, select one control characteristic from among the plurality of control characteristics based on at least one of the vehicle speed detected by the vehicle speed sensor and the weight detected by the load sensor; calculate the control pressure corresponding to the step-on amount detected by the step-on amount sensor based on the selected one control characteristic; and output a command current value according to the calculated control pressure to the solenoid proportional valve. in a case where the step-on amount detected by the step-on amount sensor is equal to or less than the predetermined step-on amount, select one control characteristic from among the plurality of control characteristics based on at least one of the vehicle speed detected by the vehicle speed sensor and the weight detected by the load sensor; calculate the control pressure corresponding to the step-on amount detected by the step-on amount sensor based on the selected one control characteristic; and output a command current value according to the calculated control pressure to the solenoid proportional valve.