To obtain a compressing/encoding/transmitting apparatus and method for road traffic information, and a decompressing/decoding/receiving apparatus and method therefor with which the compression effect of the road traffic information can be expected and a large quantity of pieces of road traffic information can be transmitted.

The compressing/encoding/transmitting apparatus has an encoding means 21 for creating encoded information by encoding the road traffic information and a compressing means 41 for creating a compressed code by compressing the encoded information. The encoding means 21 is provided with a description language character string creating means 22 for receiving the road traffic information and creating a description language such as character strings of XML, an information class word sorting means 23 for sorting words by information classes, and a dictionary creating means 25 for creating each dictionary by registering the words by the information classes.