In a hinge unit for use in an electronic apparatus, a shaft has a part held by a first member unrotatable and axially unmovable. Around the other part of the shaft, a flexible portion of a circuit board is wound. A second member is rotatable and axially unmovable with respect to the shaft. An intermediate member is faced to the second member in an axial direction and is unrotatable and axially movable with respect to the shaft. By an elastic member interposed between the shaft and the intermediate member, the intermediate member is urged towards the second member in the axial direction. The second member and the intermediate member are engaged with each other in a rotating direction by an engaging structure. The engaging structure releases the engagement with energization of the elastic member in response to a rotating force applied between the second member and the intermediate member.