A method of processing coffee beans C which comprises the step of supplying the coffee beans C into a container (10), jetting water into the container body (11) from a water-feeding channel (23) via a water-jetting port (23a) to thereby supply water into the container body (11), and allowing water to penetrate into the coffee beans C while heating the inside of the container body (11) under elevated pressure; and the step of evacuating the inside of the container body (11) to cause vaporization and expansion of water having penetrated into the coffee beans C, and thus allowing the coffee beans C to expand in a porous state, followed by milling.
