Telescopic device

A telescopic device comprising:

• a tubular structure that is telescopable;
• and
• an inner-side guide member that is disposed on an inner side of the tubular structure, wherein
• the tubular structure includes an outer belt, and an inner belt disposed on an inner side of the outer belt,
• the outer belt and the inner belt are each provided with a plurality of first protrusions and holes arranged in a row in a longitudinal direction,
• the inner-side guide member has a first spiral groove extending along the first protrusions of the inner belt,
• rotation of the inner-side guide member in one direction feeds out the outer belt and the inner belt such that the outer belt and the inner belt are spirally wound in a state of being engaged with each other, and the tubular structure is extended,
• rotation of the inner-side guide member in another direction draws in the outer belt and the inner belt such that the state of being engaged with each other and wound is disengaged, and the tubular structure is collapsed, and
• the first spiral groove includes a main part, and an end portion extending from the main part to a basal side of the inner-side guide member, wherein
• the end portion of the first spiral groove has at least one of a thread pitch that is smaller than a thread pitch of the main part of the first spiral groove, or a width that is wider than a width of the main part of the first spiral groove.