Guiding device for a tunnel boring machine, comprising • a tunnel boring machine body, • a sight rigidly connected to the body of the tunnel boring machine, comprising: - a prism arranged to reflect an incident beam so that the reflected beam is parallel to the incident beam, - an angle sensor, and - an optical beam splitter adapted to split an incident beam into two beams of the same shape as the incident beam and of divergent directions, said beam splitter being arranged to split the incident beam into a first beam directed towards the prism and a second beam directed towards the angle sensor and to return the beam reflected by the prism parallel to the incident beam, • a total station installed on a ring of a tunnel, comprising a tracking and/or distance measuring laser configured to aim at the prism and the angle sensor, the beam splitter of the sight being arranged upstream of the prism in the path of the beam emitted by the laser, said total station being configured to determine a position of the prism and the angle sensor being configured to determine a yaw angle and a pitch angle of the body of the tunnel boring machine by means of the same aiming of the prism by the laser, • an inclinometer mounted on the body of the tunnel boring machine, said inclinometer configured to measure the roll angle of said body, • a computer configured for: - determine, from the yaw, pitch and roll angles of the body of the tunnel boring machine and the position of the prism, a position and orientation of the body of the tunnel boring machine, and - determine a deviation of the position and orientation of the body of the tunnel boring machine from a theoretical position and orientation. • a tunnel boring machine body, • a sight rigidly connected to the body of the tunnel boring machine, comprising: - a prism arranged to reflect an incident beam so that the reflected beam is parallel to the incident beam, - an angle sensor, and - an optical beam splitter adapted to split an incident beam into two beams of the same shape as the incident beam and of divergent directions, said beam splitter being arranged to split the incident beam into a first beam directed towards the prism and a second beam directed towards the angle sensor and to return the beam reflected by the prism parallel to the incident beam, - a prism arranged to reflect an incident beam so that the reflected beam is parallel to the incident beam, - an angle sensor, and - an optical beam splitter adapted to split an incident beam into two beams of the same shape as the incident beam and of divergent directions, said beam splitter being arranged to split the incident beam into a first beam directed towards the prism and a second beam directed towards the angle sensor and to return the beam reflected by the prism parallel to the incident beam, • a total station installed on a ring of a tunnel, comprising a tracking and/or distance measuring laser configured to aim at the prism and the angle sensor, the beam splitter of the sight being arranged upstream of the prism in the path of the beam emitted by the laser, said total station being configured to determine a position of the prism and the angle sensor being configured to determine a yaw angle and a pitch angle of the body of the tunnel boring machine by means of the same aiming of the prism by the laser, • an inclinometer mounted on the body of the tunnel boring machine, said inclinometer configured to measure the roll angle of said body, • a computer configured for: - determine, from the yaw, pitch and roll angles of the body of the tunnel boring machine and the position of the prism, a position and orientation of the body of the tunnel boring machine, and - determine a deviation of the position and orientation of the body of the tunnel boring machine from a theoretical position and orientation. - determine, from the yaw, pitch and roll angles of the body of the tunnel boring machine and the position of the prism, a position and orientation of the body of the tunnel boring machine, and - determine a deviation of the position and orientation of the body of the tunnel boring machine from a theoretical position and orientation.