Agitating and mixing device and method for producing semiconductor sealing resin composition

An agitating and mixing device for mixing a composition containing plural kinds of pulverized materials, each of the pulverized materials having a different specific gravity, the agitating and mixing device comprising:

• a container for storing the composition, the container having a bottom surface;
• a plurality of agitating members for agitating the composition, each of the agitating members having a plate-like portion and inserted in the container so that the plate-like portion of each of the agitating members is placed on the bottom surface of the container;
• and
• a driving device for vibrating the container,
• wherein the agitating and mixing device is configured to agitate the composition stored in the container using the agitating members and then to mix the composition by vibrating the container using the driving device, and
• wherein the agitating members are configured to agitate the composition when each of the agitating members is pulled up one by one from the bottom surface of the container.