Ametrology atomic force microscope (AFM) equipped with high-resolution laser interferometers is presented. Key technologies and an uncertainty estimation of the AFM system to realize the accuracy of dimensional measurements in the order of several subnanometers are described. In the international preliminary comparison for 1-dimensional gratings, where national metrology institutes in foreign countries joined, the calibrated pitch values of the measurands by the NMIJ's metrology AFM well matched with the reference value calculated from all attendee's values within estimated uncertainties in the range from 0.15 to 0.50 nm. This shows that AFM would be one of the most promising metrological tools for dimensional measurements of fine structures with the size of a few hundreds of nanometers, and with a uncertainty with the order of 1 nm, in nanodevice fabrication and ultraprecision machining processes, if their major uncertainty components are reduced.