A toner-remaining-amount detection sensor includes a rubber member, an actuator, a transmission sensor, and a holder member which integrally holds the rubber member, the actuator, and the transmission sensor. The actuator is supported by the holder member so as to move to a first position at which the transmission sensor detects that a toner remaining amount in a toner storage container is a predetermined amount or more when a toner pressure in the toner storage container acts on the rubber member, and to move to a second position at which the transmission sensor detects that the toner remaining amount in the toner storage container falls below the predetermined amount when the toner pressure in the toner storage container does not act on the rubber member. When the actuator is at the second position, the actuator partially comes into contact with the holder member so that a gap is formed between the actuator and the rubber member.