When an image reading apparatus (1) shifts from a standby condition to a power economizing state, a buffer (15) electrically disconnects a connection path 14. Subsequently, a switch 13 electrically disconnects a power supply path 12. When the image reading apparatus 1 shifts from a power economizing state to a standby condition, the switch 13 electrically connects the power supply path 12, thereby commencing the supply of power to an image pickup section 20. Subsequently, the buffer 15 electrically connects the connection path 14. Consequently, even in a case where the supply of power to the image pickup section 20 is stopped, an electric current will not flow from the image processing section 6 to an analog-to-digital converter 22. Thus, breakage of elements included in the analog-to-digital converter 22 can be prevented. Further, when the image reading apparatus 1 is in a power economizing state, the supply of power to the image pickup section 20 and the fan 10 as well as to a light source 51 is stopped. Therefore, the image reading apparatus 1 can reduce power consumption by a greater amount than does a related image reading apparatus which extinguishes only a light source.