1. An entrance management apparatus which manages entrance through a first gate and entrance through a second gate provided inside the first gate, comprising: a first living body information input section which acquires living body information of a visitor at the first gate, a feature amount extracting section which extracts a feature amount of the living body information of the visitor based on the living body information acquired by said first living body information input section, a registration section which registers the feature amount of the living body information extracted by said feature amount extracting section in relation to entrance permission time information which defines time during which the visitor whose living body information is acquired by said first living body information input section is permitted to enter through the second gate, a second living body information input section which acquires living body information of the visitor at the second gate, a collating section which extracts a feature amount of the living body information of the visitor based on the living body information acquired by said second living body information input section and collates the extracted feature amount with the feature amount registered in said registration section, and an entrance control section which controls the entrance of the visitor whose living body information is acquired by said second living body information input section through the second gate based on the result of collation by said collating section and the entrance permission time information registered in said registration section and corresponding to the result of collation.