PURPOSE: To provide an insertion chuck device having a simple constitution that can absorb position variation and size variation among parts and can be inserted in a clearance even when the clearance between parts is small.

CONSTITUTION: A rotary body 5 is driven by a motor 2, and a planetary gear 10 supported rotatably by the rotary body 5 engages with a fixed internal gear 12 and a freely rotatable sun gear 13, and a main shaft 16 is inserted rotatably in the center part of the sun gear 13. A chuck claw 20 that grasps a male type part A is provided on the lower end part of the main shaft 16, and the chuck claw 20 is energized downward by a compression spring 19. Since the sun gear 13 is decentered relative to the rotary body 5, and the main shaft 16 is decentered relative to the sun gear 13, when the rotary body 5 is rotated, the chuck claw 20 performs cycloid motion, thereby insertion of the male type part A into the hole of a female type part becomes possible.