A fuel supplying apparatus that opens a fuel supply path using a negative pressure in a crankcase of an internal combustion engine is disclosed. A negative pressure introducing inlet of an automatic cock is connected to the crankcase of the internal combustion engine through a negative pressure communication path. A negative pressure generated in the crankcase opens an automatic cock and, thereby, the fuel supply path is opened that is to supply fuel from a fuel tank to the internal combustion engine. The negative pressure communication path communicates with a communication opening of an air cleaner through a purge path that branches from the negative pressure communication path at a halfway point thereof. The communication opening is disposed on a cleaning chamber that is formed in an air cleaner such that air filtered by an air filter flows into the communication opening. An airflow resistance increasing unit is disposed only in the inside of the communication opening, for setting an airflow resistance of the purge path to be higher than an airflow resistance of the negative pressure communication path.