A photomultiplier tube including a casing having a glass substrate with a main surface made with an insulating material, dynodes having a 1st stage to an Nth stage which are arrayed to be spaced away sequentially from a first end side to a second end side on the main surface, a photocathode installed on the first end side to be spaced away from the 1st stage dynode to emit photoelectrons, and an anode part installed on the second end side to be spaced away from the Nth stage dynode, wherein a groove is formed between two adjacent dynodes on the main surface of the glass substrate, and the 1st stage to the Nth stage dynodes are fixed on raised parts adjacent to the grooves.