1. A storage medium having stored thereon an information processing program executed by a computer of an information processing apparatus which performs a processing using acceleration data outputted by an acceleration sensor for detecting for an acceleration, in at least one axial direction, applied to a predetermined housing thereof, the information processing program causing the computer to function as: acceleration data acquisition means for repeatedly acquiring the acceleration data; accumulation vector calculation means for calculating an accumulation vector by sequentially accumulating an acceleration vector having a magnitude and a direction of the acceleration represented by the acceleration data acquired by the acceleration data acquisition means; following vector calculation means for calculating a following vector which follows, at a predetermined rate, the accumulation vector calculated by the accumulation vector calculation means, by using the acceleration data acquired by the acceleration data acquisition means; differential vector calculation means for calculating, as a differential vector, a difference between the accumulation vector and the following vector; and processing means for designating a position in a virtual world displayed by a display device using a value determined in accordance with the differential vector, and performing a predetermined processing by using the position.