A mobile apparatus capable of moving or acting autonomously while flexibly avoiding contact with a moving object in accordance with various situations is provided. In a case where a second safety condition is not satisfied because, e.g., a first target trajectory cannot be found, a second target trajectory causing a first spatial element to approach the boundary of an element passing region is searched for and determined. A robot autonomously approaches the boundary of the passable region in accordance with the second target trajectory determined as a provisional target trajectory, and stops at the position corresponding to the end point of the second target trajectory. Such movement of the robot along the second target trajectory increases the space, making it possible to prompt an object to move through the space.