A method and an apparatus for measuring the position and posture of a tunnel excavator even in a sharp bend execution, or an execution in which the gradient changes greatly. An arbitrary point of a third measurement point (C) of an excavator (5) is sighted from the second measurement point (B) so that the angle from the third measurement point (C) to the second measurement point (B) may be a predetermined angle. The position of the third measurement point (C) is calculated by using the angle of the second measurement point (B) to the third measurement point (C) and the distance and position of the arbitrary point. The posture of the excavator (5) is calculated from the angle of the third measurement point (C) to the second measurement point (B) and the horizontal level of the third measurement point (C) of the tunnel excavator (5). During the measurement, a first measurement point (A) of a known position at the back of the second measurement point (B) is sighted so that the position of the second measurement point (B) and the position of the excavator (5) are calculated.