Sunspot drawings in the 17th century are a direct source of information on solar activity before the Maunder minimum. From these data, one can restore the number of sunspot groups, as well as the time-latitude distribution of the spots known as the Maunder's butterfly diagram. One of the first drawings, made by Galilei from May 3 to 11, from June 2 to July 8 and August 19–21, are considered. These observations are distinguished by special accuracy which is not inherent to other observers of 1610s. Galilei did not indicate the exact time of observation that causes uncertainty in determining the coordinates of the spots. To define the location of spots, we use a method that minimize the difference between latitudes of the same spot on different days. As a result, coordinates and areas of 82 groups of spots were obtained. A confirmation of the accuracy of the drawings by Galilei is that most spots lie far from the equator