The Multiutility Spacecraft Charging Analysis Tool (MUSCAT), a spacecraft charging analysis software, has been developed as a collaboration work between Japan Aerospace Exploration Agency and Kyushu Institute of Technology. Laboratory experiments for fundamental code validation were carried out in both facilities' plasma chambers. MUSCAT is a particle simulation code based on particle-in-cell (PIC) and particle tracking (PT) algorithms capable of calculating the floating-body potential of a spacecraft with respect to the plasma potential. Three experiments were carried out regarding spacecraft-plasma interaction phenomena important in LEO and PEO. A Langmuir probe was used to measure the current collection and potential distribution in static plasma to validate the PIC and PT schemes. The floating potential of an object in plasma with an energetic electron component was measured to validate the floating-body calculation as well as the PT scheme. Current collection and potential distribution in the wake structure were measured to validate the PIC and PT scheme in flowing plasma condition. The experimental results and the simulation results agreed very well in all the three experiments, validating the accuracy of the MUSCAT solver.