To provide an airtight container having a tamper resisting device, which ensures water-tightness when the lid is in a closed and locked state and which makes it easy to open the lid easily when the lid is in an unlocked state.

The airtight container comprises a body formed from a flexible or semi-rigid plastic, and a lid formed from a rigid plastic. The container has projections all the way round the vicinity of the end of the external surface of the body and also a band which is parallel to the upright mouth wall of the upper end is formed around the projections so as to be removable. The lid is provided with a drooping peripheral wall that is fitted between the band and upright mouth wall of the body. Locking grooves and corresponding projections, which engage each other in order to enhance water-tightness, are formed from one level to another on the joined face of the band and drooping peripheral wall. A part of the band is provided with a cut and tab used for removing the band.