Even though a laser diode is within the operation guarantee temperature range, the rise time characteristics required to protect and maintain the writing quality right away may not be present at a lower temperature. By sufficiently increasing the rise time, a laser diode control method of the present invention makes it possible to write readily. A laser diode control device includes a temperature sensor for detecting temperature of a laser diode. When a detected temperature by the temperature sensor is equal to or below a predetermined value within the operation guarantee temperature range, a seek motor controls the position of a pickup to move the pickup to a region outside a recording region of a recording medium. In this way, a current exceeding a threshold current value is supplied to the laser diode, and the writing operation starts after the laser diode temperature is increased up to a level where the rise time characteristics required to protect and maintain the writing quality is present.