A sound signal processing apparatus includes: first amplifier which amplifies a sound signal, depending on an input level of the sound signal; and second amplifier which amplifies with a gain the sound signal amplified by first amplifier. Second amplifier automatically decreases the gain when a level of the sound signal is greater than an upper limit threshold, and second amplifier automatically increases the gain when the level of the sound signal is lower than the upper limit threshold and when the gain is lower than a predetermined value. When second amplifier increases the gain, second amplifier changes the gain at a first speed when a user has performed an operation to decrease the input level, and second amplifier changes the gain at a second speed lower than the first speed when the user has not performed the operation to decrease the input level.