Position input device and position input method

A position input device includes a coordinate system setting unit that uses position and orientation of the head of an operator in a first coordinate system to set a second coordinate system in a space including the operator, where a position on the face of the operator is designated as an origin, a transformation matrix calculation unit that calculates a transformation matrix from the first to the second coordinate system, a transformation matrix update unit that updates the transformation matrix according to a result obtained by transforming a coordinate indicating a position of the fingertip of the operator in the first coordinate system with the transformation matrix, and an indication straight line calculation unit that calculates a straight line passing through the origin of the second coordinate system and the position of the fingertip based on the transformation matrix and the position of the fingertip in the first coordinate system.