A flip-up cover mechanism. An annular body includes two opposite through
holes. A displacing member is disposed in the annular body and includes
two opposite push portions and a first flange. The push portions
respectively protrude from the annular body via the through holes. A
cover is rotatably connected to the annular body and includes a second
flange detachably engaged with the first flange. A torsion spring is
connected between the annular body and the cover. When the second flange
is engaged with the first flange, the cover is closed in relation to the
annular body and the torsion spring is twisted to provide restoring
resilience. When the push portions are respectively pushed through the
through holes, the displacing member is elastically deformed to separate
the first flange from the second flange and the cover is lifted from the
annular body by the restoring resilience provided by the torsion spring.