A medical apparatus 1 comprises: a treatment instrument 4 which is provided with a sensor 19 for detecting a position, a direction and a roll angle at a distal end portion 4C, and a bending portion 4D, and is adapted to be inserted to a target site 9G in a bronchus 9 a CT image data storing unit 13 which stores three-dimensional image data of the bronchus 9 acquired in advance an input unit 14 for setting the target site 9G a virtual endoscopic image generating unit 12 which generates a virtual endoscopic image using a line-of-sight parameter including the position, the direction and the roll angle of the distal end portion 4C detected by the sensor 19 based on the three-dimensional image data and an image processing unit 10 which performs a superimposition process and thus display operation information for inserting the distal end portion 4C to the target site 9G in superimposition on the virtual endoscopic image.
