Method for calibrating a gyrometer of an object moving in an ambient magnetic field, the method comprising the steps of: (a) acquisition - by the gyrometer, of a measured angular velocity of the object, and - by magnetic measuring means which are secured to said object, of at least two components of the magnetic field and/or of an i-th derivative of the magnetic field, around the magnetic measurement means; (b) determining, by data processing means, values of at least one calibration parameter of the gyrometer minimising a first expression defined by an estimated angular velocity of the object and at least one first magnetic equation on the components of the magnetic field and/or of an i-th derivative of the magnetic field, - the estimated angular velocity of the object being a function of the measured angular velocity and of calibration parameters of the gyrometer, and - the at least one first magnetic equation assuming that the magnetic field is uniform and stationary around the magnetic measurement means; (c) estimating a parameter representative of an error on the calibration parameters. the method being characterised in that it further comprises the step of: (d) if said parameter representative of an error is greater than a predetermined threshold, acquiring by additional acquisition means a measured linear velocity of the object and re-determining by the data processing means values of the at least one calibration parameter of the gyrometer minimising a second expression defined by the estimated angular velocity of the object and at least one second magnetic equation on the components of the magnetic field and/or of an i-th derivative of the magnetic field and on the measure linear velocity, the at least one second magnetic equation assuming only that the magnetic field is stationary around the magnetic measurement means (a) acquisition - by the gyrometer, of a measured angular velocity of the object, and - by magnetic measuring means which are secured to said object, of at least two components of the magnetic field and/or of an i-th derivative of the magnetic field, around the magnetic measurement means; - by the gyrometer, of a measured angular velocity of the object, and - by magnetic measuring means which are secured to said object, of at least two components of the magnetic field and/or of an i-th derivative of the magnetic field, around the magnetic measurement means; (b) determining, by data processing means, values of at least one calibration parameter of the gyrometer minimising a first expression defined by an estimated angular velocity of the object and at least one first magnetic equation on the components of the magnetic field and/or of an i-th derivative of the magnetic field, - the estimated angular velocity of the object being a function of the measured angular velocity and of calibration parameters of the gyrometer, and - the at least one first magnetic equation assuming that the magnetic field is uniform and stationary around the magnetic measurement means; - the estimated angular velocity of the object being a function of the measured angular velocity and of calibration parameters of the gyrometer, and - the at least one first magnetic equation assuming that the magnetic field is uniform and stationary around the magnetic measurement means; (c) estimating a parameter representative of an error on the calibration parameters.