An improved bowling alley bumper system for selectively guarding against the throwing of gutter balls. The system is a gutter (22, 24 and 26) formed of transversely divided elongated sections (28 and 30) of which at least one is pivotally displaceable by an underside actuator apparatus (66) from a first position cooperating with the remaining sections to form a conventional unguarded gutter to a second position extending above the adjacent lane bed to afford a bumper bowling effect.