To provide a recording paper roll holder device which prevents idling of a recording paper roll having a paper core and allows easy installation.

The recording paper roll holder device comprises a pair of holders. One of the holders has a driving gear to transmit the driving force of a motor through the gear to the paper roll. The holder is provided with an idling preventing mechanism 40 which comprises claw members 41-44 and springs 46-49 for energizing the claw members 41-44. Each of the claw members 41-44 swings between a biting position to bite into the inner periphery of the core 13 and a retracting position to retract within the inner diameter of the core 13. The energizing force of the springs 46-49 is weak. When the holder is fitted to the core 13, the claw members 41-44 swing to the retracting position by the weak force. During forward rotation, the claw members 41 and 43 bite into the inner periphery of the core 13 by making sliding contact therewith. The claw members 42 and 44 bite into the inner periphery of the core 13 during reverse rotation.