| 摘要 |
PROBLEM TO BE SOLVED: To provide a writing instrument without cap whose pen tip part in a barrel can be closed with a simple constitution and whose closed state before use is secured. SOLUTION: The writing instrument 1 without cap comprises a writing unit body 5 disposed in the barrel 2, and a pen point part 6 of the body 5 freely projected from and retracted in a tip part 3 of the barrel 2. The writing instrument 1 further comprises an inner cap 20 having a protrusion 21 protruded in a dome-like state in a distal end direction and provided at the tip part 3 in the barrel 2, formed of a rubber material or an elastic resin material and having a slit groove 25 having a recessed thin film part 26 and formed over a site 22b opposed to a center in an axial central direction through a substantially central part 23 of the protrusion 21 from a partial site 22a of the dome-like base 22 of the cap 20. |
