Provided is a filler powder that has a lower coefficient of thermal expansion than silica powder and is less likely to cause quality and color alteration of a resin when blended into the resin. The filler powder is made of a crystallized glass in which β-quartz solid solution and/or β-eucryptite is precipitated. The filler powder preferably has an average particle size D50 of 5 μm or less. The filler powder preferably has a coefficient of thermal expansion of 5×10−7/° C. or less in a range of 30 to 150° C.