A telescopic actuator includes a motor, an input flange rotated by the motor, a male screw member coupled to the input flange, a female screw member threadedly engaged with the male screw member, an output rod coupled to the female screw member, the output rod being moved in an axial direction thereof to output a thrust force when the input flange is rotated, and a housing inside which the male screw member and the female screw member are accommodated. The input flange is supported by the housing such that a relative movement of the input flange with respect to the housing is allowed in a radial direction but restricted in the axial direction.