A PKB (Akt) activating agent comprising a compound represented by the formula (I): ##STR00001## wherein R.sup.1 and R.sup.2: H, a hydrocarbon group or a heterocyclic group or R.sup.1 and R.sup.2 form a ring in cooperation with the adjacent carbon atom; R.sup.3: H, a hydrocarbon group or a heterocyclic group; W: represents a group represented by the formulas: ##STR00002## wherein ring A: an optionally substituted benzene ring; ring B: an optionally substituted 5- to 7-membered nitrogen-containing heterocycle; R.sup.4: an aliphatic hydrocarbon group substituted with an aromatic group and further optionally substituted, or an acyl group containing an aromatic group; R.sup.5: H, C.sub.1-6 alkyl or acyl; R.sup.4c: an aromatic group, an aliphatic hydrocarbon group or acyl; and X: O or S; Y: O, S or NH; and ring C: an optionally substituted benzene ring, or a salt or a prodrug thereof, and use of the activating agent in prevention or treatment of depression, anxiety, manic-depressive psychosis or PTSD are provided.