A compact one-shot 3He cryostat has been fabricated for use of X-ray detector at a temperature of 0.4K. The cryostat employed two valves availably: one for controlling a charcoal adsorption pump, and the other for faciliating liquid helium handling. The use of two valves enabled us to decrease the amount of liquid helium including the transfer loss. Superconducting thin wires with a very low copper ratio were useful to generate a magnetic field of moderate strength, while suppressing the heat flow into the cryogenic region.
