Provided are a hot-melt adhesive having high flowability in a molten state and exhibiting high adhesion strength in bonding PP nonwoven fabrics and further exhibiting high adhesion strength in bonding PE film-PP nonwoven fabric, and a base polymer for a hot-melt adhesive. The hot-melt adhesive contains (A) a propylene-based polymer satisfying the following (Ai) to (Aiv), and (B) an olefin-based copolymer satisfying the following (Bi) and (Bii); and the base polymer for a hot-melt adhesive consists of a mixture of (A) a propylene-based polymer satisfying the following (Ai) to (Aiv) and (B) an olefin-based copolymer satisfying the following (Bi) and (Bii) and satisfies the following (1) and (2). (Ai) the melting point is 120°C or lower, (Aii) the Mw is 10,000 to 150,000, (Aiii) the Mw/Mn is 2.5 or less, (Aiv) the penetration is 8 or less, (Bi) the penetration is 15 or more, (Bii) the melting point is 90°C or higher, (1) the tensile elastic modulus at 23°C is 400 MPa or less, and (2) the semi-crystallization time at 23°C is 20 minutes or less.