Conservation of the Kazeno-matsubara Coastal Forest in Noshiro City, northern Japan was discussed based on vegetational and floristic investigations conducted in 2000 and 2001. This coastal forest is composed of planted Pinus thunbergii and divided into two parts. One is composed of old pines nearly 150 years old and the other are young pines nearly 30-70 years old. Some pines have recently been attacked and killed by Bursaphelencus xylophilus. The vegetational investigation showed that old pines were going to decline due to deciduous broad-leaved trees which had invaded into the pine forest through the succession process in the past 50 years. In the floristic investigation, 93 families and 371 species of vascular plants were recorded. It seems that the use of pesticide to kill harmful nematodes and the removal of the deciduous trees should be done to protect the pine forest. Certain plant species such as wild orchids and coastal plants and the area where these species are distributed should be protected for nature conservation.