A profile measuring apparatus which is configured to measure a profile of a gear having a plurality of teeth which are periodically aligned in a circumferential direction and extend in a direction different from the circumferential direction, the profile measuring apparatus comprising: an irradiation section configured to irradiate a measurement light to a measurement area of the gear; an imaging section configured to obtain an image of the measurement area including a position to which the measurement light is irradiated by the irradiation section; a stage configured to place the gear thereon; a coordinate calculation section configured to calculate a position of the measurement area based on an image detected by a detection section; and a positioning mechanism configured to drive and control a relative position of the imaging section and the stage relative to each other, wherein the positioning mechanism is configured to set the relative position of the imaging section and the stage, based on an information with respect to the direction of the ridge line of a tooth of the gear in the measurement area of the gear, to move at least one of the stage and the imaging section relative to each other, wherein the positioning mechanism is configured to set a relative position of the irradiation section to the object and a relative position of the imaging section to the gear so that the measurement light is irradiated to the measurement area from a first direction and the image in the measurement area is taken from a second direction different from the circumferential direction of the gear, wherein the positioning mechanism includes a rotational movement section which is configured to move at least one of the irradiation section and the gear relative to each other so that a position of the measurement area to which the measurement light is irradiated is moved in a third direction in the circumferential direction of the gear so that the plurality of teeth aligned in the circumferential direction is measured; wherein the positioning mechanism further includes a relative movement section which is configured to move the irradiation section and the gear relative to each other in a fourth direction along the direction of the ridge lines of the teeth, further comprising a holding section configured to hold the irradiation section and the imaging section, wherein the rotational movement section moves the holding section and gear relative to each other. an irradiation section configured to irradiate a measurement light to a measurement area of the gear; an imaging section configured to obtain an image of the measurement area including a position to which the measurement light is irradiated by the irradiation section; a stage configured to place the gear thereon; a coordinate calculation section configured to calculate a position of the measurement area based on an image detected by a detection section; and a positioning mechanism configured to drive and control a relative position of the imaging section and the stage relative to each other, wherein the positioning mechanism is configured to set the relative position of the imaging section and the stage, based on an information with respect to the direction of the ridge line of a tooth of the gear in the measurement area of the gear, to move at least one of the stage and the imaging section relative to each other, wherein the positioning mechanism is configured to set a relative position of the irradiation section to the object and a relative position of the imaging section to the gear so that the measurement light is irradiated to the measurement area from a first direction and the image in the measurement area is taken from a second direction different from the circumferential direction of the gear, wherein the positioning mechanism includes a rotational movement section which is configured to move at least one of the irradiation section and the gear relative to each other so that a position of the measurement area to which the measurement light is irradiated is moved in a third direction in the circumferential direction of the gear so that the plurality of teeth aligned in the circumferential direction is measured; wherein the positioning mechanism further includes a relative movement section which is configured to move the irradiation section and the gear relative to each other in a fourth direction along the direction of the ridge lines of the teeth, further comprising a holding section configured to hold the irradiation section and the imaging section, wherein the rotational movement section moves the holding section and gear relative to each other.