PURPOSE: To enable the efficient operation to separate a cap of a cultivation bottle into an upper lid and a cap body by mechanizing the operation.

CONSTITUTION: The objective mechanism for separating a cap of a mushroom cultivation bottle is capable of pressing a cap, having a filter therein and used in a mushroom cultivation bottle into the cap body and an upper lid, pressed into the top surface of the body and attached thereto. A pair of rollers 10 and 12 having a nipping and pressing surface for nipping and pressing the outer peripheral surface in an engaging part of the upper lid of the cap with the body are arranged so as to oppose the nipping and pressing surfaces. The rotating directions of the rollers 10 and 12 are regulated to those for passing the cap through the rollers and the peripheral speeds of the respective rollers are set at different ones so as to revolve and pass the cap through the rollers in its passage therethrough.