「そろそろ」に関する従来の研究はその時間的な側面を取り挙げるものが多いが、本稿では時間性とモダリティの相関の仕方に着目した。「そろそろ」は出来事成立時期への近づきを描写するのみならず、成立に向かって近づいていく含蓄的な過程も含意する。「そろそろ」の時間性と文のモダリティの相互作用 により、含意される時間的な推移と共に出来事実現の必然性や当為性も増していき、出来事成立の頃合いの時期に到達し、成立時期が近づいていることが表現される。 更に、本稿では、「そろそろ」の諸用法を手掛かりにしながら、動作の様態を表す用法から始まり、抽象化しながら時間的な意味に派生し、頃合い判断・当為性判断を表す用法に至った「そろそろ」の意味派生の過程についても考察した。This paper reveals how the Japanese temporal adverb sorosoro modifies the time of event actualization. It expresses that the actualization time is closely approaching, thereby implying an underlying temporal progression towards the actualization. This progression is not only temporal, but also implicative, frequently enforced by co-appearing focus particle mo which triggers similar connotations. Along with the implied temporal progression, the necessity to carry out the action increases gradually, peaking at a given criterion time. Thus, sorosoro expresses the notion that the time is ripe for an event to occur by temporally indicating its approaching actualization, while modally denoting the necessity to carry it out. Furthermore, this paper illustrates the derivative process of sorosoro's meaning as one originating from a mimetic expression of gradual movement. First, it acquires a temporal meaning through semantic abstraction. Then through expanded usages in nominal sentences, it goes on to acquire its modal meanings of judgement and necessity. Since it is often used to express the judgement that the time is suitable for an event to occur, it frequently appears with nominal expressions such as koro（just the right time）or kisetsu（season）, which have connotations of 'temporal suitability'.