To secure the safety of police officers and workers performing an accident processing on a road by preparing a transmitter provided with a switch member to be in the state of 'switch on' when an engaging/disengaging piece is detached.

When it is assumed that an approaching vehicle during driving while looking away travels a vehicle passing zone and is to pass through the tape main body 5 of a flexible control member 4, since the required part of the tape main body 5 is held or fixed by the elastic holding part 10 of the fixing means 8 of a supporting member 1 for a barricade, the engaging/ disengaging piece 7 of the flexible control member is detached from the receiving plate of a supporting box 22. Then, the switch member 21 is turned to the state of 'switch on', radio waves 31 are transmitted from the transmitter 20 to a receiver 30 at a traffic accident scene A and the receiver 30 rings an alarming machine 32. Thus, the police officers and the workers at the scene recognize that the approaching vehicle is traveling toward the accident scene A by the alarm.