This paper deals with large deflections of thin, straight and tapered cantilever beams set up almost vertically. The results are as follows : (1) When a cantilever beam is placed almost vertically, the deformation of the beam is very small for the load lower than a certain critical value, while it becomes very large suddenly for the load exceeding the said critical value. (2) When the inclination of the beam exceeds the vertical angle, two deformation forms can exist for the load greater than the above-mentioned critical value. As the inclination increases gradually from a small value, the deformation form changes continuously, and when the inclination reaches a certain value exceeding an angle of 90°, it jumps from the 1st form to the 2nd. (3) When the load is applied slightly off-centered and more over the inclination passes through an angle of 90°, the beam turns to the direction of the eccentric load and the deformation form transfers from the 1st form to the 2nd. (4) In the actual fishing, it is experimentally known that if we incline the fishing rod by an angle of more than 90°, we often lose the control of the rod because the rod tends to turn clockwise or counterclockwise. This fact can be explained by this dynamical analysis.