PURPOSE: To easily test a gas detection in a distribution board to which a gas piece is applied by a method wherein a gas-piece mounting stand to which the gas piece is attached is heated.

CONSTITUTION: A terminal screw 22 which is used to connect a breaker and a terminal screw 24 which is used to connect every apparatus 24 are installed on a metal plate 20 for a terminal stand 18. When the screws 22, 24 are loosened, the connection resistance of their parts is increased, and the terminal stand 18 generates heat. A gas piece 2 which is attached to the metal plate 20 generates heat due to the generated heat, a microcapsule which is contained in a coating layer on a main-body part 2A for the gas piece 2 is burst due to the heat, and a gas inside the microcapsule is discharged. Since the generated gas is at a high temperature as compared with room temperature, the gas is collected by a collection cover so as to be detected by a gas sensor. Thereby, a gas detection can be tested easily in a distribution board to which the gas piece 2 is applied.