Light curves of integrated visual brightness for the periodic comet Tempel 1, 9P during 1972, 1983, 1994, and 2005 appearances were constructed and studied. The values of photometrical parameters H₀, n, and H₁₀ were calculated and secular fading was studied for the comet. The light curve of the comet near the impact time was constructed and compared with comet's water production rate. The photometrical peculiarities of the comet and long-term evolution of comet's activity will probably change after the impact.