A Geiger-Muller counter tube includes an enclosing tube, an anode conductor, a cathode conductor, an inert gas, and a quenching gas. The enclosing tube is at least partially cylindrical and has a sealed space. The anode conductor includes an anode electrode and a linear first metal lead portion. The anode electrode is arranged inside the space and formed in a rod shape. The first metal lead portion is connected to the anode electrode and supported at an end of the enclosing tube. The cathode conductor includes a cylindrical cathode electrode and a linear second metal lead portion. The cathode electrode surrounds a peripheral area of the anode electrode inside the space. The second metal lead portion is connected to the cathode electrode and supported at the end of the enclosing tube. The cathode electrode has a side surface through a part of which a through-hole passes.