Insertion system

An insertion system comprising:

• an insertion apparatus including an insertion section to be inserted into a subject;
• a fiber sensor arranged in the insertion section and configured to detect a bend shape of a desired shape detection range of the insertion section;
• at least one attitude sensor arranged in the insertion apparatus and configured to detect at least one of a first rotational change quantity related to a change quantity of rotation about an axis in a longitudinal direction of the insertion apparatus at an arrangement position, and a first directional change quantity related to a change quantity of a direction of the longitudinal direction of the insertion apparatus at the arrangement position;
• and
• a processor including hardware, the processor being configured to:
• calculate attitude information of the insertion apparatus including a change quantity of rotation of the bend shape about an axis in the longitudinal direction of the insertion apparatus and a change quantity of a longitudinal direction of the insertion apparatus, based on at least one of the first rotational change quantity and the first directional change quantity detected by the attitude sensor;
• and
• calculate attitude shape information, based on the bend shape detected by the fiber sensor and the calculated attitude information.