Hydraulic system for working machine

A hydraulic system for a working machine, comprising:

• a hydraulic pump to output an operation fluid;
• a first hydraulic actuator;
• a second hydraulic actuator;
• a first control valve to control the first hydraulic actuator;
• a second control valve to control the second hydraulic actuator, the second control valve being arranged on a downstream side of the first control valve;
• a pressure increasing portion to increasing a pressure of the operation fluid;
• a first discharge fluid tube connected to any one of the first control valve and the second control valve and connected to the pressure increasing portion;
• a second discharge fluid tube connected to the first discharge fluid tube and configured to discharge the operation fluid separately from the first discharge fluid tube;
• a float switching valve having an allowance position, a prevention position, and a float position,
• the allowance position blocking the second discharge fluid tube and allowing the operation fluid to flow to the pressure increasing portion,
• the prevention position unblocking the second discharge fluid tube and preventing the operation fluid from flowing to the pressure increasing portion,
• the float position allowing the operation fluid of the first hydraulic actuator to be discharged from a third discharge fluid tube other than the first discharge fluid tube and the second discharge fluid tube.