To improve detaching/attaching operability of a shouldering belt when shouldering or removing a knapsack body of a satchel, a rucksack, a day bag or the like on/from a back of a human, and to secure an excellent mounting condition in which the whole of a back support part of the knapsack body adheres to the back of the human.

The satchel 1 includes: a back support part 3 which touches the back of a human by an adhering condition; and a knapsack body 5 which has a housing part in the inside. The satchel 1 includes one right and left pair of back load belts 7 which are turned to be hung at right and left shoulders of the human 2 so that the knapsack body 5 is loaded on the back, supports the upper end part of the back support part 3 of an upper portion of the knapsack body 5, and supports the lower end side of the back support part 3 of the knapsack body 5.