  We report on a large X-ray flare from the Lindroos binary system HD 560
during a pointed ROSAT PSPC observation. Strong magnetic activity is expected
for the late-type component (a G dwarf star and post-T Tauri Star candidate).
The system is unresolved in the ROSAT image. Therefore, although not expected
from a theoretical point of view, it can not be excluded that the flare has
erupted on the primary, a late-B type star. We discuss the luminosity and
temperature evolution comparing the quiescent and the flare state of HD 560,
and present arguments for the G star as host of the flare.
