An improved panel siding installation device enables a worker installing panel siding on a building structure such as a house to accurately and efficiently measure the distance between edges of adjacent siding panels. This distance is known as the “reveal distance” of the lap siding. In addition to accurately measuring the distance between edges of siding panels, the present invention also supports the siding panel while it is being installed. This support provides some assistance to the installation worker and enables an installation working to more quickly and accurately install siding panels on a structure.