PROBLEM TO BE SOLVED: To include an image of an image area to be visually confirmed in an image received from a terminal of another site in respective terminals disposed at respective sites.SOLUTION: An MCU 70 adjusts pieces of image data from terminals at respective sites in an image adjustment (A) unit 72c according to an image adjustment signal received from a terminal 100a of a site A. The image adjustment (A) unit 72c cuts out image data from a terminal of a site to be indicated by ID data from image coordinates on the basis of ID data of a terminal of the site A selected by an operator and the image coordinates that is an adjustment parameter, and enlarges the cut-out image data. An image composition (A) unit 72d combines image data from a terminal of a site B or C and the image data obtained by subjecting the image data from the terminal of the site A to cut-out processing and enlargement processing to obtain one image data. An encoder (A) unit 72e encodes the composite image data, and the encoded data is transmitted from a transmission unit 72g to a terminal 100b or 100c.
