Abstract: A capless retractable marking pen has excellent sealing capability and a simple structure. The capless retractable marking pen includes a hollow sealing member for receiving a writing tip when the pen is in nonuse, and an opening and closing member for opening and closing an opening provided at a front end of the sealing member. The opening and closing member has a cover part pivotably fixed at a first end thereof to a lower edge portion of a front opening of the sealing member, an extending part extended from a second end of the cover part, and fixed at a front end portion thereof to the ink cartridge, and a hole provided at the extending part so that the writing tip can be extended and retracted through the hole.