A surface texture measuring apparatus includes an X axis displacement mechanism and a Y axis displacement mechanism displacing a measurable object having an interior wall along an XY plane; a measurement sensor measuring a surface texture of the interior wall without contact; a Z axis displacement mechanism displacing the measurement sensor in a Z axis direction orthogonal to the XY plane and bringing the measurement sensor to face the interior wall; a W axis displacement mechanism displacing the measurement sensor facing the interior wall in a normal direction of the interior wall; and a θ axis displacement mechanism displacing the measurement sensor facing the interior wall along the interior wall.