PURPOSE: To provide an abnormality detecting system for a distribution line carrier communications system capable of quickly recovering a state where a system goes down.

CONSTITUTION: This system is the distribution line carrier communications system composed so that return communication from each of slave stations 2 to a master station 1 is performed when transmission from the master station 1 to each of the slave stations 2 is performed individually between the master station 1 and plural slave stations 2 connected mutually with a distribution line 3, and re-transmission can be performed when transmission failure or a reception defect, etc., occurs, and it is provided with a first detecting means 4 which detects the number of times of the transmission failure and a second detecting means 5 which detects the number of times of the reception defect.