A display processing terminal device connectable to a photosensor-equipped unit that includes a photosensor configured to receive light and acquire predetermined photometric data relating to the received light, comprising: a display portion operable to perform a display process with any one of plural display directions being specified as a display direction of a display screen, said display direction (AR5, AR6) being a direction so that a user can easily view the display screen relative to a viewing direction (SR3, SR4) of the user; an interface portion operable to make communication with said photosensor-equipped unit when the display processing terminal device is connected to said photosensor-equipped unit; a screen display control portion operable to execute a display direction setting process during connection for setting said display direction of said display portion based upon transmission information relating to said display direction acquired from said photosensor-equipped unit, when the display processing terminal device is connected to said photosensor-equipped unit; and a direction determination information holding portion operable to hold display direction determination information for determining a display direction of the display screen of said display portion when the display processing terminal device is connected to said photosensor-equipped unit, wherein said transmission information includes photosensor identification information for identifying a type of said photosensor, and said screen display control portion is operable to determine an instruction content of said display direction determination information based upon said photosensor identification information, and to execute said display direction setting process during connection, characterised in that said screen display control portion is adapted to, when the photosensor identification information indicates that the photosensor is an illumination photometry sensor, determine that the instruction content of said display direction determination information instructs that a side of the display processing terminal device where the photosensor-equipped unit is connected becomes an upper direction of the display screen of the display portion, and when the photosensor identification information indicates that the photosensor is a color measuring sensor, determine that the instruction content of said display direction determination information instructs that a side of the display processing terminal device where the photosensor-equipped unit is connected becomes a lower direction of the display screen of the display portion. a display portion operable to perform a display process with any one of plural display directions being specified as a display direction of a display screen, said display direction (AR5, AR6) being a direction so that a user can easily view the display screen relative to a viewing direction (SR3, SR4) of the user; an interface portion operable to make communication with said photosensor-equipped unit when the display processing terminal device is connected to said photosensor-equipped unit; a screen display control portion operable to execute a display direction setting process during connection for setting said display direction of said display portion based upon transmission information relating to said display direction acquired from said photosensor-equipped unit, when the display processing terminal device is connected to said photosensor-equipped unit; and a direction determination information holding portion operable to hold display direction determination information for determining a display direction of the display screen of said display portion when the display processing terminal device is connected to said photosensor-equipped unit, wherein said transmission information includes photosensor identification information for identifying a type of said photosensor, and said screen display control portion is operable to determine an instruction content of said display direction determination information based upon said photosensor identification information, and to execute said display direction setting process during connection, characterised in that said screen display control portion is adapted to, when the photosensor identification information indicates that the photosensor is an illumination photometry sensor, determine that the instruction content of said display direction determination information instructs that a side of the display processing terminal device where the photosensor-equipped unit is connected becomes an upper direction of the display screen of the display portion, and when the photosensor identification information indicates that the photosensor is a color measuring sensor, determine that the instruction content of said display direction determination information instructs that a side of the display processing terminal device where the photosensor-equipped unit is connected becomes a lower direction of the display screen of the display portion.