The present invention relates to a grinder, comprising a grinding unit is installed between a receptacle and a base. A grinding wheel and a grinding base of the grinding unit are detachably and respectively installed on a transmission shaft and at the bottom side of the receptacle, and a bottom cover of an automatic open/close control device utilizes an engaging button for being combined with a combination part of a fasten cover installed at the bottom side of a follower member, so the bottom cover can be detachably installed at the bottom opening of a housing. Accordingly, components which may have food powders adhered thereon, such as the grinding wheel and the grinding base of the grinding unit and the follower member, the housing and the bottom cover of the automatic open/close control device are capable of being detached for cleaning, so the food hygiene can be ensured.