A mass analyzer includes a main substrate, an upper substrate adhered to the main substrate, and a lower substrate. A mass analysis room (cavity) is formed in the main substrate and penetrates from an upper surface of the first main substrate to a lower surface of the first main substrate. A vertical direction (Z direction) to the main substrate by the upper substrate, both sides of the lower substrate, a travelling direction (X direction) of charged particles and a right angle to the Z direction by the main substrate, and both sides of a right-angled direction (Y to Z direction) and the X direction by a side surface of the main substrate are surrounded. A central hole is open in the side plate of the main substrate that the charged particles enter. The charged particles enter the mass analysis room through the central hole formed in the first main substrate.