An intra-oral scanner comprising: a body and inside it an optical output unit (60, 221), an optical output control unit (80, 222), an optical sensing unit (70, 223) and a data transmitting unit (90, 224); and an insertion body (10, 401) and inside it an optical system (40, 211), a guide (30, 403) and an optical system driving unit (50, 212); wherein the insertion body (10, 401) projects from the body along a reference axis B so as to be insertable into an oral cavity, wherein the optical output unit (60, 221) is configured to output an output light, the optical output control unit (80, 222) is configured to rotate the optical output unit (60, 221) along a reference axis C which is perpendicular to reference axis B to change the emission angle of the output light or to slide the optical output unit (60, 221) parallel to a further reference axis A which is perpendicular to the reference axis B and C to control an emission position of the output light, the optical system (40, 211) is configured to reflect the output light with the emission position controlled by the optical output control unit to a tooth or teeth being scanned, the optical system driving unit (50, 212) is configured to rotate the optical system (40, 211) along the further reference axis A so as to control a reflection angle of the output light, the guide (30, 403) is configured to guide the optical system (40, 211) to move within a preset distance from the optical output unit, the optical sensing unit (70, 223) is configured to sense the light reflected by the optical system at the tooth or teeth being scanned and to convert the sensed light into an electrical signal, and the data transmitting unit (90, 224) is configured to transmit information of the electrical signal, information of the emission position of light and information of the reflection angle to a three-dimensional data generating unit to generate three-dimensional scanning model for the tooth or teeth being scanned, and the insertion body (10, 401) is configured to protect the path of the output light and the light reflected by the optical system (40, 211), and includes a top surface projecting in parallel with the reference axis B, a bottom surface having a predetermined angle to the top surface in order to protect the path of the output light and the light reflected by the optical system and an optical transmission window, which enables the output light reflected by the optical system to travel to the tooth or teeth being scanned, and the light reflected at the tooth or teeth being scanned to travel to the optical system. a body and inside it an optical output unit (60, 221), an optical output control unit (80, 222), an optical sensing unit (70, 223) and a data transmitting unit (90, 224); and an insertion body (10, 401) and inside it an optical system (40, 211), a guide (30, 403) and an optical system driving unit (50, 212); wherein the insertion body (10, 401) projects from the body along a reference axis B so as to be insertable into an oral cavity, wherein the optical output unit (60, 221) is configured to output an output light, the optical output control unit (80, 222) is configured to rotate the optical output unit (60, 221) along a reference axis C which is perpendicular to reference axis B to change the emission angle of the output light or to slide the optical output unit (60, 221) parallel to a further reference axis A which is perpendicular to the reference axis B and C to control an emission position of the output light, the optical system (40, 211) is configured to reflect the output light with the emission position controlled by the optical output control unit to a tooth or teeth being scanned, the optical system driving unit (50, 212) is configured to rotate the optical system (40, 211) along the further reference axis A so as to control a reflection angle of the output light, the guide (30, 403) is configured to guide the optical system (40, 211) to move within a preset distance from the optical output unit, the optical sensing unit (70, 223) is configured to sense the light reflected by the optical system at the tooth or teeth being scanned and to convert the sensed light into an electrical signal, and the data transmitting unit (90, 224) is configured to transmit information of the electrical signal, information of the emission position of light and information of the reflection angle to a three-dimensional data generating unit to generate three-dimensional scanning model for the tooth or teeth being scanned, and the insertion body (10, 401) is configured to protect the path of the output light and the light reflected by the optical system (40, 211), and includes a top surface projecting in parallel with the reference axis B, a bottom surface having a predetermined angle to the top surface in order to protect the path of the output light and the light reflected by the optical system and an optical transmission window, which enables the output light reflected by the optical system to travel to the tooth or teeth being scanned, and the light reflected at the tooth or teeth being scanned to travel to the optical system.