To carry out the delivery of a driving signal of an electromagnetic actuator in an optional timing, accelerate the number of revolutions of a loom and efficiently feed a driving power in a noncontact state to a driving control part of the electromagnetic actuator for driving a weft yarn engaging unit.

This apparatus for length measuring and storing of the weft yarn for a loom comprises an electromagnetic solenoid 12 fixed on the inside of a yarn winding surface-forming unit 10 and an engaging pin 12a is driven to emerge and sink in a hole 10c by excitation and demagnetization with the electromagnetic solenoid 12. A driving circuit 13 is mounted on the outside of the electromagnetic solenoid 12 and a driving power receiving part 14 and a driving control signal receiving part 15 are fixed onto the yarn winding surface-forming unit 10. A driving power feeding part 17 for feeding the driving power in a noncontact state to the driving power receiving part 14 and a driving control signal transmitting part 18 for transmitting a driving control signal in a noncontact state to the driving control signal receiving part 15 are fixed in positions separate from the yarn winding surface-forming unit 10. The driving control signal receiving part 15 and the driving control signal transmitting part 18 are composed of a transmitting and receiving part of a communication device using an infrared communication method.