Floral differentiation of strawberry is induced by low temperature in short daylength. The effect of low temperature on floral differentiation of strawberry 'Toyonoka' was observed through microscope. The plants were grown in controlled growth chamber at day/night temperature 20/17℃ and 17/14℃, day-length 10 hours for 20 days. Under 20/17℃, the flower buds were initiated in 10 days, inflorescence differentiated in 12 days, and flower differentiation completed in 20 days. However, under 17/14℃, the flower buds were initiated in 8 days, inflorescence differentiated in 12 days, and flower differentiation completed in 18 days. The duration of apical meristem induced to floral initiation was 2 days earlier at 17/14℃ than at 20/17℃.