A silica-based LP11 mode rotator, which is one of the basic and indispensable optical components for space division multiplexing, with multiple tapered trenches is proposed. Compared with the conventional interference-based LP11 mode rotator with a simple L-shape waveguide, the proposed LP11 mode rotator has many advantages in a mode conversion efficiency, an insertion loss, and a fabrication tolerance because the operation principle is based on the adiabatic mode conversion. By using an approach of the shortcut to adiabaticity, the proposed device is effectively miniaturized rather than the standard tapered structures. Among the LP11 mode rotators in the silica-based mode multi/demultiplexers, the proposed type will be a considerably promising candidate.