A holding device, includes: a holding portion configured to hold a shunt resistor; a spacer portion extending from the holding portion and abutting on a front surface of a substrate on which a monitoring unit configured to monitor a current value of a current flowing through the shunt resistor is mounted; and an engaging portion extending from the holding portion and having an engaging claw to be engaged with a back surface of the substrate. The spacer portion separates the holding portion and the substrate from each other such that a connection portion which electrically connects the shunt resistor and the monitoring unit is visible.