Polypropylene-based resin expanded bead and method for producing same

A method for producing a polypropylene-based resin expanded bead having a tubular shape with a through-hole that penetrates through an inside in an axial direction thereof, the method comprising:

• granulating to obtain a multilayer resin particle comprising a core layer made of a polypropylene-based resin and having a tubular shape with a through-hole that penetrates through an inside in an axial direction thereof, and a cover layer made of a polyolefin-based resin and covering a side peripheral surface of the core layer;
• and
• foaming the multilayer resin particle to obtain the expanded bead, after the granulating, wherein
• an average hole diameter dr of the through-hole of the multilayer resin particle is less than 0.25 mm,
• a ratio dr/Dr of the average hole diameter dr of the through-hole to an average outer diameter Dr of the multilayer resin particle is 0.4 or less,
• the core layer and the cover layer each comprise a coloring pigment, and
• a melt mass flow rate MFRS of the polyolefin-based resin constituting the cover layer, as measured under conditions of a temperature of 230° C. and a load of 2.16 kg in accordance with JIS K7210-1:2014, is greater than 15 g/10 min.