PURPOSE: To provide a length measuring device which can measure the length of a continuous material correctly, can prevent deformation generated in the continuous material, and can easily respond to change of the measuring length, wherein operations for returning the material for aligning a measurement start position and for cutting and drawing out the head part of the continuous material are eliminated.

CONSTITUTION: After a microcomputer 20 is started, a clutch is operated. A draw-out conveyor 4 and a delivery conveyor 5 are operated by starting a motor 7. A head part of a tire material is moved from the draw-out conveyor 4 to the delivery conveyor 5, and the head part of the tire material is detected by a sensor 11. An encoder 9 receives a detection signal from the sensor 11 and starts measuring a moved quantity of the delivery conveyor 5. When a delivery quantity of the tire material by the encoder 9 becomes L2, a cutting device 6 is operated so as to cut off the tire material. After the tire material is cut off, the tire material which is cut by only the delivery conveyor 5 is moved to a next stage.