To solve the problem wherein since a conventional envelope comprising a body part in which an object is put and a flap part 1 to seal which is connected to the body part, is put in a machine and put out from it automatically many times by a paper head adjusting function of the machine when printing operation such as address printing or the like is performed with a machine such as a widely used ink-jet printer or the like lately, the flap part 1 is caught in the machine at the printing operation in either way the flap part 1 is kept extended or folded, and the operation is interrupted to decrease efficiency of the printing operation and it becomes a cause to make the expensive machine get out of order.

When the envelop is sealed with the flap part 1, the flap part 1 is inserted into a slit 3 formed on the body part 2 near closing part to be sealed at the printing operation so that the flap part 1 is fixed temporarily to the body part 2 to prevent the flap part 1 from being caught in the machine.