PURPOSE: To provide a brake control device which can run a vehicle safely even if a defect is caused in a pneumatic supply system.

CONSTITUTION: A first pipeline system is extended from a first pneumatic source A through a brake valve 100, a rear system relay valve 101 and a rear system air control valve 102 to a rear side wheel cylinder. A second pipeline system 32 is extended from a second pneumatic source B through a brake valve 100, a front system relay valve 101a and a front system air control valve 102a to a front side wheel cylinder 15. Further, a detecting means is provided which is connected between the first pipeline system 31 and the second pipeline system 31 and adapted to detect a defect in pipeline systems according to a difference in pressure from both pipeline systems.