a fuel filtration device includes a first filter normally used to filter foreign substances in fuel , a second filter used to filter foreign substances in fuel only in a state where a degree of clogging of the first filter is larger than a predetermined level , and a regulating device for regulating a flow of fuel through the second filter . the regulating device disables the flow of fuel through the second filter to limit the filtering of foreign substances through the second filter when the degree of clogging of the first filter is equal to or smaller than the predetermined level . the regulating device enables the flow of fuel through the second filter to permit the filtering of foreign substances through the second filter when the degree of clogging of the first filter is larger than the predetermined level .