With the expansion of GPS users, various types of GPS have appeared in the market. Accuracy is very much required for precise surveying, whereas cost performance is more important for many purposes such as car navigation system, field check investigation, etc. The accuracy of “Germin GPS-38”, a handy GPS marketed for recreational use, is examined in this paper. The error ranges for X (longitude), Y (latitude) and Z (altitude) direction are respectively-38m to +52m, -130m to +74m, and -289m to +71m by single GPS. In order to improve the accuracy, we found that the pseudo-differential method is effective. The error ranges of X, Y, Z direction changed to -40m to +49m, -31m to +33m and -66m to +46m respectively. By averaging 10 minutes data at the same point with pseudo-differential method, 14m distance error in X-Y plain is expected, which is acceptable for ground truth investigation for Remote Sensing data.