An information acquisition system comprising: a server; a database; and a portable information device comprising: an image sensor configured to output an image of an object; a position information acquisition portion configured to output position information of the device; an orientation sensor configured to output orientation information of the device; an input portion for inputting post information; a wireless communication portion configured to receive relevant information on the object based on the position information and the orientation information from the server; a display portion configured to display the image of the object, the relevant information on the object, and the input portion, wherein the display portion comprises a touch panel and the input portion comprises a text field and a touch screen-type keyboard for inputting characters; and a control portion configured to display the input portion on the display portion for inputting post information and to transmit through the wireless communication portion the post information about the object, camera identification information, and building structure identification information, while displaying an imaging image, which is the image of the object and being output from the image sensor, on the display portion, wherein the relevant information is stored in the database in association with positions of registered objects in a map, wherein the server is configured to retrieve the relevant information by selecting among the registered objects that object which is closest from the position represented by the position information in the direction represented by the orientation information. a server; a database; and a portable information device comprising: an image sensor configured to output an image of an object; a position information acquisition portion configured to output position information of the device; an orientation sensor configured to output orientation information of the device; an input portion for inputting post information; a wireless communication portion configured to receive relevant information on the object based on the position information and the orientation information from the server; a display portion configured to display the image of the object, the relevant information on the object, and the input portion, wherein the display portion comprises a touch panel and the input portion comprises a text field and a touch screen-type keyboard for inputting characters; and a control portion configured to display the input portion on the display portion for inputting post information and to transmit through the wireless communication portion the post information about the object, camera identification information, and building structure identification information, while displaying an imaging image, which is the image of the object and being output from the image sensor, on the display portion, an image sensor configured to output an image of an object; a position information acquisition portion configured to output position information of the device; an orientation sensor configured to output orientation information of the device; an input portion for inputting post information; a wireless communication portion configured to receive relevant information on the object based on the position information and the orientation information from the server; a display portion configured to display the image of the object, the relevant information on the object, and the input portion, wherein the display portion comprises a touch panel and the input portion comprises a text field and a touch screen-type keyboard for inputting characters; and a control portion configured to display the input portion on the display portion for inputting post information and to transmit through the wireless communication portion the post information about the object, camera identification information, and building structure identification information, while displaying an imaging image, which is the image of the object and being output from the image sensor, on the display portion, wherein the relevant information is stored in the database in association with positions of registered objects in a map, wherein the server is configured to retrieve the relevant information by selecting among the registered objects that object which is closest from the position represented by the position information in the direction represented by the orientation information.