In order to investigate the causes of deterioration of the mural paintings of Takamatsuzuka Tumulus, it is very important to clarify temperature and humidity variation in the stone chamber. We estimated how the environmental conditions surrounding the stone chamber and the internal works affect temperature and humidity in the stone chamber by making use of numerical simulation. The simulation was based on the measurement data and records of Takamatsuzuka Tumulus in the past. We made an analytical model taking into account the mound and the conservation facility and set up each condition in terms of factors which influence temperature and humidity in the stone chamber. We considered records of the past as far as possible to makethe model and set up the boundary conditions. In this study, we investigated the effect of different mound covering conditions — vegetation, waterproof sheet and temporary shelter —on temperature and humidity in the stone chamber during the operation of the conservation facility. The obtained main results are as follows.1. Cutting vegetation and putting waterproof sheet on the mound in September 2003 was one of the main causes of temperature rise in the stone chamber around 2004.2. Setting up the temporary shelter on the mound was one of the main causes of temperature fall in the stone chamber after the removal of the waterproof sheet in September 2004
