To provide an ampoule made of a resin which prevents a rupture opening at the time of circulation from occurring by increasing the rigidity of a recess section, and which can easily be unsealed at the time of use.

This ampoule made of the resin has a peripheral wall 2 which surrounds the axis O, and the annular recess section 4 which is formed over the total periphery of the peripheral wall 2 partitions the peripheral wall 2 into a head section 2a and a barrel section 2b. By breaking the recess section 4, a spout A is formed on the upper end of the barrel section 2b. On the recess section 4, at least one flat plate piece 6 which radially projects from the recess section 4 on a plane perpendicularly crossing the axis O, and integrally connects the head section side end surface 4a with the barrel section side end surface 4b is installed.