An electrical junction box comprising: a casing configured to be mounted in a vehicle; a start electrical component (120A, 220) housed in the casing in a first space thereof and to which a current is supplied at least at a start of the vehicle configured to control supply of current to a vehicle electrical component for starting the vehicle, the start electrical component (120A, 220) including an electrical component case (20a, 220a) and a terminal portion, the terminal portion being housed in the electrical component case (20a, 220a) and having a contact (FC, MC); an operational electrical component (14, 15, 20, 220, 20B) housed in the casing in a second space thereof and to which a current is supplied at least during an operation of the vehicle; and a partition heat shield wall disposed between the start electrical component (120A, 220) and the operational electrical component (14, 15, 20, 220, 20B); the electrical junction box further comprises: a circuit board housed in the casing, on which the start electrical component (120A, 220) and the operational electrical component (14, 15, 20, 220, 20B) are mounted, the circuit board having a circuit pattern connected to the terminal portion; a plate member housed in the casing, disposed such that at least the start electrical component (120A, 220) is disposed between the plate member and the circuit board; wherein the plate member is a second circuit board having a circuit pattern connected to the circuit pattern of the circuit board; and the electrical junction box further comprises a second partition heat shield wall disposed between the start electrical component (120A, 220) and the second circuit board. a casing configured to be mounted in a vehicle; a start electrical component (120A, 220) housed in the casing in a first space thereof and to which a current is supplied at least at a start of the vehicle configured to control supply of current to a vehicle electrical component for starting the vehicle, the start electrical component (120A, 220) including an electrical component case (20a, 220a) and a terminal portion, the terminal portion being housed in the electrical component case (20a, 220a) and having a contact (FC, MC); an operational electrical component (14, 15, 20, 220, 20B) housed in the casing in a second space thereof and to which a current is supplied at least during an operation of the vehicle; and a partition heat shield wall disposed between the start electrical component (120A, 220) and the operational electrical component (14, 15, 20, 220, 20B); the electrical junction box further comprises: a circuit board housed in the casing, on which the start electrical component (120A, 220) and the operational electrical component (14, 15, 20, 220, 20B) are mounted, the circuit board having a circuit pattern connected to the terminal portion; a plate member housed in the casing, disposed such that at least the start electrical component (120A, 220) is disposed between the plate member and the circuit board; wherein the plate member is a second circuit board having a circuit pattern connected to the circuit pattern of the circuit board; and the electrical junction box further comprises a second partition heat shield wall disposed between the start electrical component (120A, 220) and the second circuit board. a circuit board housed in the casing, on which the start electrical component (120A, 220) and the operational electrical component (14, 15, 20, 220, 20B) are mounted, the circuit board having a circuit pattern connected to the terminal portion; a plate member housed in the casing, disposed such that at least the start electrical component (120A, 220) is disposed between the plate member and the circuit board; wherein the plate member is a second circuit board having a circuit pattern connected to the circuit pattern of the circuit board; and the electrical junction box further comprises a second partition heat shield wall disposed between the start electrical component (120A, 220) and the second circuit board.