To provide a fixed construction of a bladder capable of being reduced in the cost.

A pressing member 5 to press the circumference 3 of the bladder 1 against the inner peripheral side is installed in the fixed construction of the bladder to fix the bladder 1 to the inner peripheral side of a container 10. The periphery 3 of the bladder 1 is pressed against the inner circumference of the container 10 with the pressing member 5 to fix the bladder 1. In order to prevent the bladder 1 from slipping out of place, a restricting means such as a stepped part A may be installed in the inner peripheral part of the container.