An exhaust duct and boiler can appropriately collect solid particles in flue gas by way of being provided with: a flue (40) in which flue gas can flow; a first hopper (61) that is provided in the flue (40) and that can collect solid particles (PA) in the flue gas; and a first baffle plate (71) and a second baffle plate (72) that are resisting members capable of blocking the flow of solid particles (PA) from the first hopper (61).