A hydraulic system comprising: a hydraulic pump; a control valve for supplying an operating pressure from the hydraulic pump to an actuator of a working machine; and a pilot pressure supply unit for supplying a pilot pressure to the control valve, wherein the pilot pressure supply unit includes: an electromagnetic proportional valve that has a detent-type emergency manual operation function configured to manually open a pilot oil passage and to generate a pilot pressure for the control valve; a controller for controlling a degree of opening of the electromagnetic proportional valve in accordance with an operation of an operation lever; and a pilot pressure switching unit for switching the pilot pressure supply unit between an on-loading state and an unloading state, the hydraulic system being characterized in that the pilot pressure switching unit includes: a pilot pressure unloading solenoid valve for switching a pilot pressure between the on-loading state and the unloading state by energization; and an emergency operation activation switch that is activated in a case where the electromagnetic proportional valve cannot be controlled by the controller and that is configured to control an energization state of the pilot pressure unloading solenoid valve, wherein the pilot pressure switching unit is configured to control a pilot pressure supply unit such that the pilot pressure supply unit is in the unloading state when the electromagnetic proportional valve is manually opened, and is configured to control the pilot pressure supply unit such that the pilot pressure supply unit is in the on-loading state after the electromagnetic proportional valve is manually opened. an electromagnetic proportional valve that has a detent-type emergency manual operation function configured to manually open a pilot oil passage and to generate a pilot pressure for the control valve; a controller for controlling a degree of opening of the electromagnetic proportional valve in accordance with an operation of an operation lever; and a pilot pressure switching unit for switching the pilot pressure supply unit between an on-loading state and an unloading state, the hydraulic system being characterized in that the pilot pressure switching unit includes: a pilot pressure unloading solenoid valve for switching a pilot pressure between the on-loading state and the unloading state by energization; and an emergency operation activation switch that is activated in a case where the electromagnetic proportional valve cannot be controlled by the controller and that is configured to control an energization state of the pilot pressure unloading solenoid valve, wherein the pilot pressure switching unit is configured to control a pilot pressure supply unit such that the pilot pressure supply unit is in the unloading state when the electromagnetic proportional valve is manually opened, and is configured to control the pilot pressure supply unit such that the pilot pressure supply unit is in the on-loading state after the electromagnetic proportional valve is manually opened. a pilot pressure unloading solenoid valve for switching a pilot pressure between the on-loading state and the unloading state by energization; and an emergency operation activation switch that is activated in a case where the electromagnetic proportional valve cannot be controlled by the controller and that is configured to control an energization state of the pilot pressure unloading solenoid valve, wherein the pilot pressure switching unit is configured to control a pilot pressure supply unit such that the pilot pressure supply unit is in the unloading state when the electromagnetic proportional valve is manually opened, and is configured to control the pilot pressure supply unit such that the pilot pressure supply unit is in the on-loading state after the electromagnetic proportional valve is manually opened.