The present invention provides: hydroxyapatite, a principal component of teeth, which has a high degree of hardness, is to be used in a device for forming a membrane on a tooth surface by spraying the tooth surface with a powder, and is favorable for forming a membrane having an extremely low solubility in acid in a short period of time and favorable for forming a membrane from a powder that conforms to the color tone of the tooth in a short period of time； and a membrane-forming powder that uses hydroxyapatite having a color tone modifier added thereto. The present invention produces: a hydroxyapatite powder sintered at 600-1,350 DEG C in an inert gas atmosphere； a powder obtained by subjecting the hydroxyapatite powder sintered at 600-1,350 DEG C to plasma exposure, or to plasma exposure and the application of mechanical energy； and a membrane-forming powder obtained by adding a color tone modifier to these hydroxyapatite powders.本發明提供一種膜形成用粉體，該膜形成用粉體使用在藉由對於牙齒表面噴射粉體，以於牙齒表面上形成膜的裝置；本發明的膜形成用粉體使用作為牙齒主成分且添加色調調整劑之羥磷灰石，該羥磷灰石適宜用以於短時間內形成高硬度、對於酸的溶解度極低的膜，且適宜用以於短時間內形成適合牙齒色調的粉體膜；為了提供本發明的膜形成用粉體，於惰性氣氛下，以600～1350℃燒結羥磷灰石粉體，對以600～1350℃燒結的羥磷灰石粉體，加施電漿照射、或電漿照射與機械性能量而獲得粉體，進一步於該羥磷灰石粉體，添加色調調整劑來製造膜形成用粉體。
