PURPOSE: To execute the buying and selling between counter parties in an automatic matching buying and selling form and a video interactive form by using key stations connectable to each other.

CONSTITUTION: Each key station 202,... has a keyboard 240, mouse 242. integrated screen display 238, etc., and integrated terminal controllers 214 and 216 function as common interfaces between the key stations 202,... and networks 218 and 220. Processed data are given between the key stations related to the buying and selling in an automatic matching buying and selling form and a video interactive form in a system 200 through the controllers 214 and 216. A common informal slip generating scheme related to both buying and selling forms is used and informal buying and selling slips are collected and transmitted to an office data base in rear by means of the controllers 214 and 216 regardless of the executed buying and selling form.