To provide a one-touch opening refill container which is constituted of a simple structure, easy to perform refilling operation, and free from the generation of an overflow of contents when refilling.

The refill container used for refilling contents into a rigid container equipped with a spout nozzle is characterized by having a refill container body 4 and a mouth plug 1. The mouth plug 1 has a sleeve 2 for fixing the refill container body 4, a spout 3 into which the spout nozzle of the rigid container can be inserted, and a seal plate 5 to tightly seal the refill container having a flow rate regulating means 6 that regulates the flow rate when making contents flow out.