PROBLEM TO BE SOLVED: To provide an insertion unit having a configuration capable of easily positioning a leading end part side of an insertion body in front of a bent portion by enabling to allow the bent portion to easily pass.SOLUTION: The insertion unit includes an outer insertion body 1 forming a slit 2 along the insertion direction S in at least a leading end side an inner insertion body 20 freely insertable forward and backward to inside the outer insertion body 1 and freely projecting forward from a leading end 1s of the outer insertion body 1 and a guide member 10 formed with a bending portion 11 at the leading end side, freely insertable forward and backward to the inside of the outer insertion body 1, and freely projecting forward from the leading end 1s of the outer insertion body 1.
