To solve such problems that a conventional table of a collapsible chair with a side table cannot be sideways extended without the chair becoming unstable at vacancy and is hard to use since it is not in a position to which a user naturally stretches hands.

In this collapsible chair where a rod-like material is formed in a rectangular frame body shape to be erected and arranged, a pair of side frame bodies using upper horizontal rods as armrests and erected rods as legs are oppositely arranged at a prescribed interval in the chair width direction, a seat surface and a backrest surface constituted by stretching a flexible sheet material are arranged between a pair of side frame bodies, and a pair of side frame bodies are reduced in a chair width directional interval by a rotational movement of respective connecting parts, a side table having a support member for rotatably supporting one edge side and holding the one side edge in a state of being almost horizontally extended outside is arranged in a proper height position of the side frame bodies, and an auxiliary table for further extending a table top is arranged on the table.