A fiber spatial coupling device comprising: a detachable process fiber that guides laser light ; an optical system that collects the laser light into the process fiber ; and a main body that holds the optical system , and has a supply port for supplying gas to a space between the process fiber and the optical system , wherein a filter is linked to the supply port , and gas that has passed through the filter is supplied to an inside of the main body through the supply port , characterized in that the fiber spatial coupling device further comprises: a dehumidifier linked to the supply port , and gas that has passed through the dehumidifier is supplied to the inside of the main body through the supply port , a pressure release unit configured to release the gas in an inside of the main body when a pressure of an inside of the main body exceeds a predetermined reference value, a receptacle that holds the process fiber in the main body ; a disconnection detection circuit including the process fiber and the receptacle , a pump having a discharge side coupled to the filter and the dehumidifier and a pump control unit configured to operate the pump only when an off-state of laser light and disconnection are detected by the disconnection detection circuit . a detachable process fiber that guides laser light ; an optical system that collects the laser light into the process fiber ; and a main body that holds the optical system , and has a supply port for supplying gas to a space between the process fiber and the optical system , wherein a filter is linked to the supply port , and gas that has passed through the filter is supplied to an inside of the main body through the supply port , characterized in that the fiber spatial coupling device further comprises: a dehumidifier linked to the supply port , and gas that has passed through the dehumidifier is supplied to the inside of the main body through the supply port , a pressure release unit configured to release the gas in an inside of the main body when a pressure of an inside of the main body exceeds a predetermined reference value, a receptacle that holds the process fiber in the main body ; a disconnection detection circuit including the process fiber and the receptacle , a pump having a discharge side coupled to the filter and the dehumidifier and a pump control unit configured to operate the pump only when an off-state of laser light and disconnection are detected by the disconnection detection circuit . a dehumidifier linked to the supply port , and gas that has passed through the dehumidifier is supplied to the inside of the main body through the supply port , a pressure release unit configured to release the gas in an inside of the main body when a pressure of an inside of the main body exceeds a predetermined reference value, a receptacle that holds the process fiber in the main body ; a disconnection detection circuit including the process fiber and the receptacle , a pump having a discharge side coupled to the filter and the dehumidifier and a pump control unit configured to operate the pump only when an off-state of laser light and disconnection are detected by the disconnection detection circuit . <EOS>